feat(exam): let ONLINE exams take ESSAY/BOTH form, add grading-sheet API

Frontend half of the backend change: ExamPage no longer disables the
form Select or force-resets it to CHOICE when administrationMethod is
ONLINE (backend's assertOnlineIsChoiceOnly is gone, matching gate
removed here). Also wires up GET .../grading-sheet as
useGetGradingSheetQuery — RecordResultModal wiring (show candidate
answers, prefill auto-computed CHOICE scores) is next.

apps/backoffice/src/app/features/exam/api/exam-api.ts

@@ -12,6 +12,7 @@ import type {
   CreateIncidentPayload,
   ResolveIncidentPayload,
   RegradeOutcome,
+  GradingSheet,
 } from '../types/exam';
 
 const examApi = baseApi.injectEndpoints({
@@ -101,6 +102,15 @@ const examApi = baseApi.injectEndpoints({
       }),
       invalidatesTags: ['Api'],
     }),
+    /** The candidate's answers plus auto-computable CHOICE scores, for RecordResultModal. */
+    getGradingSheet: builder.query<
+      GradingSheet,
+      { examId: string; profileId: string }
+    >({
+      query: ({ examId, profileId }) =>
+        `/exam-attempts/exam/${examId}/candidate/${profileId}/grading-sheet`,
+      providesTags: ['Api'],
+    }),
   }),
   overrideExisting: false,
 });
@@ -119,4 +129,5 @@ export const {
   useRecordIncidentMutation,
   useResolveIncidentMutation,
   useRegradeAttemptMutation,
+  useGetGradingSheetQuery,
 } = examApi;

apps/backoffice/src/app/features/exam/pages/ExamPage/index.tsx

@@ -255,12 +255,6 @@ function ExamForm({
                   onChange={setForm}
                   size="sm"
                   required
-                  disabled={adminMethod === "ONLINE"}
-                  description={
-                    adminMethod === "ONLINE"
-                      ? t("exam.form.onlineChoiceOnlyHint")
-                      : undefined
-                  }
                 />
                 <Select
                   label={t("exam.detail.administration")}
@@ -270,14 +264,7 @@ function ExamForm({
                     { value: "ONLINE", label: t("exam.form.online") },
                   ]}
                   value={adminMethod}
-                  onChange={(value) => {
-                    setAdminMethod(value);
-                    // Online exams are graded automatically, and that only
-                    // has an answer model for CHOICE — matches the backend
-                    // rule (online_exam_requires_choice_form), not just a
-                    // UI nicety.
-                    if (value === "ONLINE") setForm("CHOICE");
-                  }}
+                  onChange={setAdminMethod}
                   size="sm"
                   required
                 />

apps/backoffice/src/app/features/exam/types/exam.ts

@@ -136,6 +136,24 @@ export type RegradeOutcome =
   | { graded: true; resultId: string }
   | { graded: false; reason: string };
 
+/** One question's row on the staff grading sheet — the candidate's own
+ * answer plus the auto-computable score, where one exists. */
+export interface GradingSheetQuestion {
+  questionId: string;
+  form: QuestionForm;
+  points: number;
+  answerText: string | null;
+  selectedOptionId: string | null;
+  selectedOptionText: { en?: string; am?: string } | null;
+  /** null means "no auto-score" — examiner enters one by hand. */
+  autoScore: number | null;
+}
+
+export interface GradingSheet {
+  attemptStatus: 'IN_PROGRESS' | 'SUBMITTED' | 'EXPIRED';
+  questions: GradingSheetQuestion[];
+}
+
 export interface RecordAttendancePayload {
   registrationId: string;
   status: AttendanceStatus;

apps/backoffice/src/app/i18n/locales/am.ts

@@ -260,7 +260,6 @@ export const am: Translations = {
       both: "ሁለቱም",
       offline: "ከመስመር ውጪ",
       online: "በመስመር",
-      onlineChoiceOnlyHint: "የመስመር ላይ ፈተናዎች በራስ-ሰር ይመዘገባሉ፣ ይህም ለምርጫ ጥያቄዎች ብቻ ይሰራል።",
       sum: "ድምር",
       average: "አማካይ",
       percentage: "መቶኛ",

apps/backoffice/src/app/i18n/locales/en.ts

@@ -259,7 +259,6 @@ export const en = {
       both: 'Both',
       offline: 'Offline',
       online: 'Online',
-      onlineChoiceOnlyHint: 'Online exams are graded automatically, which only works for multiple choice.',
       sum: 'Sum',
       average: 'Average',
       percentage: 'Percentage',