feat: Refactor medical and sea service verification pages

- Split MedicalVerificationPage into MedicalVerificationPage and SeaServiceVerificationPage for better separation of concerns.
- Update navigation to include separate entries for Sea Service Verification and Medical Verification.
- Enhance sea service columns to display additional vessel information and days served.
- Add translations for new and updated labels in both English and Amharic.
- Introduce seaServiceDays helper function to calculate days served based on engagement and discharge dates.
- Remove deprecated MedicalCertificatePage from the portal.
- Update routing to direct to the new sea service and medical pages.

libs/api/src/lib/features/seafarer/index.ts

@@ -1,2 +1,3 @@
 export * from './seafarer.types';
 export * from './seafarer-api';
+export * from './seafarer.helpers';

libs/api/src/lib/features/seafarer/seafarer.helpers.ts

@@ -0,0 +1,23 @@
+/**
+ * Days served on one engagement, counted inclusively — embarkation and
+ * discharge days both count. The same arithmetic the API uses for approved
+ * sea time (`SeafarerRecordService.approvedSeaTime`), so the figure a seafarer
+ * sees while typing is the figure the eligibility gate will credit.
+ *
+ * `null` until both dates are set or while they are out of order.
+ */
+export function seaServiceDays(
+  engagementDate: string | null | undefined,
+  dischargeDate: string | null | undefined,
+): number | null {
+  if (!engagementDate || !dischargeDate) return null;
+  const from = Date.UTC(...dateParts(engagementDate));
+  const to = Date.UTC(...dateParts(dischargeDate));
+  if (Number.isNaN(from) || Number.isNaN(to) || to < from) return null;
+  return Math.round((to - from) / 86_400_000) + 1;
+}
+
+function dateParts(value: string): [number, number, number] {
+  const [y, m, d] = value.slice(0, 10).split('-').map(Number);
+  return [y, (m || 1) - 1, d || 1];
+}