feat: complete offline write support with mutation queue + runtime SW cache config

- Add offline CRUD to todoRepo, budgetRepo, reservationRepo, accommodationRepo,
  dayRepo, tripRepo, fileRepo with optimistic Dexie writes and mutation queue
- Wire all store slices (todo, budget, reservations, files, dayNotes, assignments,
  tripStore) through repos for offline-aware writes
- Cover archive/unarchive, file toggleStar/update/delete, assignment create/delete,
  day title/notes update offline paths
- Migrate service worker from generateSW to injectManifest (custom sw.ts) with
  runtime-configurable api-data (7d/500) and map-tiles (30d/1000) cache policies
- Add Settings → Offline cache configuration UI with save/reset and live SW postMessage
- Extend mutationQueue flush to cover all writable Dexie tables

client/src/repo/dayRepo.ts

@@ -1,5 +1,6 @@
 import { daysApi } from '../api/client'
 import { offlineDb, upsertDays } from '../db/offlineDb'
+import { mutationQueue, generateUUID } from '../sync/mutationQueue'
 import type { Day } from '../types'
 
 export const dayRepo = {
@@ -15,4 +16,24 @@ export const dayRepo = {
     upsertDays(result.days)
     return result
   },
+
+  async update(tripId: number | string, dayId: number | string, data: Record<string, unknown>): Promise<{ day: Day }> {
+    if (!navigator.onLine) {
+      const existing = await offlineDb.days.get(Number(dayId))
+      const optimistic: Day = { ...(existing ?? {} as Day), ...(data as Partial<Day>), id: Number(dayId) }
+      await offlineDb.days.put(optimistic)
+      await mutationQueue.enqueue({
+        id: generateUUID(),
+        tripId: Number(tripId),
+        method: 'PUT',
+        url: `/trips/${tripId}/days/${dayId}`,
+        body: data,
+        resource: 'days',
+      })
+      return { day: optimistic }
+    }
+    const result = await daysApi.update(tripId, dayId, data)
+    offlineDb.days.put(result.day)
+    return result
+  },
 }