feat(theme): add semantic tokens, focus ring, and reduced-motion support

Adds the layer feature code has been missing: tokens that name a role — page
surface, subtle border, danger — instead of a colour. Every one resolves to a
Mantine variable rather than a literal, so they follow the colour scheme for
free and cannot drift from the theme. A parallel palette of raw hexes would
have recreated exactly the problem this exists to fix.

Also closes three accessibility gaps that had no implementation anywhere in the
codebase: no :focus-visible rule, no screen-reader-only utility, and no global
prefers-reduced-motion handling.

The focus work found a real bug, and nearly introduced a worse one. Mantine
already rings its own controls, so the first attempt deferred to it with
`outline: none` on .mantine-focus-auto. That suppressed Mantine's ring without
replacing it, leaving portal buttons with no focus indicator at all — and it
only showed up in one app, because which rule won depended on stylesheet order.
The rules use identical values, so overlapping them is invisible and safe;
opting out is not. The focus test now asserts computed outline width and style,
not just pixels, since a screenshot alone would not have caught this.

`status-tone.ts` establishes the six-tone vocabulary that the 48 scattered
status→colour maps will eventually collapse onto. Nothing consumes it yet.

No visual change: the 8 existing baselines pass unmodified.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

libs/shared/src/index.ts

@@ -2,6 +2,7 @@ export * from './lib/theme/palettes';
 export * from './lib/theme/base-theme';
 export * from './lib/theme/ema-theme';
 export * from './lib/theme/portal-theme';
+export * from './lib/theme/status-tone';
 export * from './lib/date/date-displayer';
 export * from './lib/date/use-date-displayer';
 export * from './lib/date/ethiopic';

libs/shared/src/lib/theme/semantic.css

@@ -0,0 +1,178 @@
+/* ============================================================================
+   Semantic tokens.
+
+   These name a *role* — "the page background", "a subtle border", "danger" —
+   rather than a colour. Feature code should reach for these instead of a hex,
+   because a hex cannot follow the colour scheme and a Mantine shade index
+   (`gray.5`) says nothing about why that shade was chosen.
+
+   Every token resolves to a Mantine variable rather than a literal. That is
+   deliberate: Mantine already recomputes its own variables under
+   [data-mantine-color-scheme], so tokens defined in terms of them switch for
+   free and can never drift from the theme. A parallel palette of raw hexes
+   would recreate exactly the problem this layer exists to fix.
+
+   Loaded once per app, after Mantine's CSS.
+   ============================================================================ */
+
+:root {
+  /* --- Surfaces ---------------------------------------------------------- */
+  /* The page itself, a raised card, and a recessed well. */
+  --ema-surface-page: var(--mantine-color-gray-0);
+  --ema-surface-raised: var(--mantine-color-white);
+  --ema-surface-sunken: var(--mantine-color-gray-1);
+
+  /* --- Borders ----------------------------------------------------------- */
+  /* Subtle separates rows; strong outlines an input or a focused container. */
+  --ema-border-subtle: var(--mantine-color-gray-2);
+  --ema-border-strong: var(--mantine-color-gray-4);
+
+  /* --- Text -------------------------------------------------------------- */
+  /* Secondary must stay a *text* colour: it has to clear 4.5:1, not 3:1, so
+     it deliberately sits darker than the gray-5 that reads as "dimmed". */
+  --ema-text-primary: var(--mantine-color-gray-9);
+  --ema-text-secondary: var(--mantine-color-gray-7);
+  --ema-text-disabled: var(--mantine-color-gray-5);
+
+  /* --- Status ------------------------------------------------------------
+     Six tones, which is the entire vocabulary a status needs. Domain statuses
+     map onto these rather than each picking their own colour.
+
+     `-fg` is text on the app background; `-bg` is a tint to sit that text on.
+     Both are needed because a badge and a label have different contrast
+     requirements against the same surface. */
+  --ema-status-success-fg: var(--mantine-color-green-8);
+  --ema-status-success-bg: var(--mantine-color-green-0);
+  --ema-status-warning-fg: var(--mantine-color-yellow-8);
+  --ema-status-warning-bg: var(--mantine-color-yellow-0);
+  --ema-status-danger-fg: var(--mantine-color-red-8);
+  --ema-status-danger-bg: var(--mantine-color-red-0);
+  --ema-status-info-fg: var(--mantine-color-blue-8);
+  --ema-status-info-bg: var(--mantine-color-blue-0);
+  --ema-status-pending-fg: var(--mantine-color-orange-8);
+  --ema-status-pending-bg: var(--mantine-color-orange-0);
+  --ema-status-neutral-fg: var(--mantine-color-gray-7);
+  --ema-status-neutral-bg: var(--mantine-color-gray-1);
+
+  /* --- Focus -------------------------------------------------------------
+     One ring for the whole platform. Sized to stay visible against both a
+     white card and a tinted surface. */
+  --ema-focus-ring: var(--mantine-primary-color-filled);
+  --ema-focus-ring-width: 2px;
+  --ema-focus-ring-offset: 2px;
+}
+
+[data-mantine-color-scheme='dark'] {
+  /* Dark is not light inverted. Surfaces lift with elevation rather than
+     dropping, and text steps down from white rather than up from black. */
+  --ema-surface-page: var(--mantine-color-dark-8);
+  --ema-surface-raised: var(--mantine-color-dark-7);
+  --ema-surface-sunken: var(--mantine-color-dark-9);
+
+  --ema-border-subtle: var(--mantine-color-dark-4);
+  --ema-border-strong: var(--mantine-color-dark-3);
+
+  --ema-text-primary: var(--mantine-color-gray-0);
+  --ema-text-secondary: var(--mantine-color-gray-4);
+  --ema-text-disabled: var(--mantine-color-dark-2);
+
+  /* Saturated mid-shades go muddy on a dark ground; these step lighter so the
+     foreground still clears 4.5:1 and the tint stays distinguishable. */
+  --ema-status-success-fg: var(--mantine-color-green-4);
+  --ema-status-success-bg: var(--mantine-color-green-9);
+  --ema-status-warning-fg: var(--mantine-color-yellow-4);
+  --ema-status-warning-bg: var(--mantine-color-yellow-9);
+  --ema-status-danger-fg: var(--mantine-color-red-4);
+  --ema-status-danger-bg: var(--mantine-color-red-9);
+  --ema-status-info-fg: var(--mantine-color-blue-4);
+  --ema-status-info-bg: var(--mantine-color-blue-9);
+  --ema-status-pending-fg: var(--mantine-color-orange-4);
+  --ema-status-pending-bg: var(--mantine-color-orange-9);
+  --ema-status-neutral-fg: var(--mantine-color-gray-4);
+  --ema-status-neutral-bg: var(--mantine-color-dark-5);
+}
+
+/* ============================================================================
+   Focus.
+
+   The codebase had no :focus-visible rule anywhere, which is the single
+   largest accessibility gap in it. :focus-visible rather than :focus so a
+   mouse click does not leave a ring behind — that is the behaviour that gets
+   focus rings deleted from designs in the first place.
+   ============================================================================ */
+
+/* Mantine already rings its own controls (`.mantine-focus-auto:focus-visible`
+   resolves to the same 2px solid primary). This rule is the safety net for
+   everything it does not own: plain anchors, custom elements, and the
+   UnstyledButtons this codebase uses for its own controls.
+
+   Note there is deliberately no `outline: none` opt-out for the Mantine
+   classes. An earlier attempt at one suppressed Mantine's working ring and
+   left portal buttons with no focus indicator at all — which of the two rules
+   won came down to stylesheet order, and that differs between the apps.
+   Matching values mean overlap is invisible, so overlap is the safe default. */
+:focus-visible {
+  outline: var(--ema-focus-ring-width) solid var(--ema-focus-ring);
+  outline-offset: var(--ema-focus-ring-offset);
+}
+
+/* ============================================================================
+   Screen-reader-only utility.
+
+   No equivalent existed anywhere in the codebase, so anything needing a text
+   alternative had nowhere to put it.
+   ============================================================================ */
+
+.ema-sr-only {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  margin: -1px;
+  overflow: hidden;
+  /* clip-path rather than the legacy clip: it does not force a layer and is
+     not deprecated. */
+  clip-path: inset(50%);
+  white-space: nowrap;
+  border: 0;
+}
+
+/* A skip link is sr-only until focused, then must be plainly visible. */
+.ema-skip-link {
+  position: absolute;
+  top: 0;
+  left: 0;
+  z-index: 9999;
+  padding: 0.75rem 1.25rem;
+  background: var(--ema-surface-raised);
+  color: var(--ema-text-primary);
+  border: 1px solid var(--ema-border-strong);
+  border-radius: 0 0 var(--mantine-radius-md) 0;
+  font-weight: 600;
+  text-decoration: none;
+  /* Off-screen rather than display:none, so it stays focusable. */
+  transform: translateY(-150%);
+}
+
+.ema-skip-link:focus-visible {
+  transform: translateY(0);
+}
+
+/* ============================================================================
+   Reduced motion.
+
+   Honour the OS setting globally. Animation is not removed outright — a
+   near-instant transition still conveys that something changed, without the
+   movement that triggers vestibular symptoms.
+   ============================================================================ */
+
+@media (prefers-reduced-motion: reduce) {
+  *,
+  *::before,
+  *::after {
+    animation-duration: 0.01ms !important;
+    animation-iteration-count: 1 !important;
+    transition-duration: 0.01ms !important;
+    scroll-behavior: auto !important;
+  }
+}

libs/shared/src/lib/theme/status-tone.ts

@@ -0,0 +1,51 @@
+/**
+ * The platform's status vocabulary.
+ *
+ * There are 48 separate status→colour maps across the codebase, each deciding
+ * independently what "pending" looks like. They disagree. The fix is not one
+ * bigger map — domain statuses genuinely differ per feature — but one small set
+ * of *tones* that every domain maps onto, so the colour decision is made six
+ * times instead of forty-eight.
+ *
+ * `semantic.css` carries the CSS-variable form of these for stylesheet use.
+ * This module is for the many places that need a Mantine `color` prop instead.
+ */
+
+export type StatusTone =
+  | 'success'
+  | 'warning'
+  | 'danger'
+  | 'info'
+  | 'pending'
+  | 'neutral';
+
+/**
+ * Tone → Mantine colour name.
+ *
+ * Deliberately the only place a tone becomes a colour. Changing the platform's
+ * idea of "warning" is an edit here, not a sweep through 48 files.
+ */
+export const STATUS_TONE_COLOR: Record<StatusTone, string> = {
+  success: 'green',
+  warning: 'yellow',
+  danger: 'red',
+  info: 'blue',
+  pending: 'orange',
+  neutral: 'gray',
+};
+
+/**
+ * Tone → CSS custom properties, for inline styles and stylesheets.
+ *
+ * Returns variable references rather than resolved colours so the values keep
+ * following the active colour scheme.
+ */
+export function statusToneVars(tone: StatusTone): {
+  color: string;
+  background: string;
+} {
+  return {
+    color: `var(--ema-status-${tone}-fg)`,
+    background: `var(--ema-status-${tone}-bg)`,
+  };
+}