Add reserve drill assignment API

scripts/verify-campaign-save-normalization.mjs

@@ -36,6 +36,7 @@ try {
     normalizeCampaignSortieItemAssignments,
     resetCampaignState,
     setCampaignState,
+    setCampaignReserveTrainingAssignment,
     setFirstBattleReport
   } = await server.ssrLoadModule('/src/game/state/campaignState.ts');
   const { battleScenarios } = await server.ssrLoadModule('/src/game/data/battles.ts');
@@ -134,6 +135,26 @@ try {
       cappedReserveDrills['unit-96'] === undefined,
     `Expected reserve drill assignments without a roster filter to stay capped: ${JSON.stringify(cappedReserveDrills)}`
   );
+  storage.clear();
+  storage.set(
+    campaignStorageKey,
+    JSON.stringify({
+      version: 1,
+      updatedAt: '2026-07-03T11:30:00.000Z',
+      step: 'third-camp',
+      roster: [{ id: 'liu-bei', name: 'Liu Bei', faction: 'ally' }]
+    })
+  );
+  loadCampaignState();
+  const assignedReserveDrill = setCampaignReserveTrainingAssignment(' liu-bei ', 'class-practice');
+  const ignoredReserveDrill = setCampaignReserveTrainingAssignment('ghost-unit', 'bond-practice');
+  const clearedReserveDrill = setCampaignReserveTrainingAssignment('liu-bei');
+  assert(
+    assignedReserveDrill.reserveTrainingAssignments['liu-bei'] === 'class-practice' &&
+      ignoredReserveDrill.reserveTrainingAssignments['ghost-unit'] === undefined &&
+      clearedReserveDrill.reserveTrainingAssignments['liu-bei'] === undefined,
+    `Expected reserve drill assignment API to trim, filter, and clear per-officer focus ids: ${JSON.stringify({ assignedReserveDrill, ignoredReserveDrill, clearedReserveDrill })}`
+  );
 
   resetCampaignState();
   const firstScenario = battleScenarios['first-battle-zhuo-commandery'];