fix(sync): re-hydrate active trip store on reconnect/online (H1) (#1181)

setRefetchCallback was dead code, so on reconnect the queue flushed and Dexie
re-seeded but the open trip's Zustand store was never refreshed — a
collaborator's edits made while we were offline didn't appear until navigating
away and back.

- new tripStore.hydrateActiveTrip(): silent refresh of the active trip's
  collaborative state (days/places/packing/todo/budget/reservations/files),
  no resetTrip and no isLoading toggle so there's no splash on reconnect
- syncTriggers wires setRefetchCallback to it (WS layer awaits the flush hook
  first) and re-hydrates open trips after the online-event syncAll; cleared on
  unregister
- websocket exposes getActiveTrips() for the online-event path
- tests: refetch wiring + ordering, silent hydrate without reset/splash

client/src/store/tripStore.ts

@@ -66,6 +66,7 @@ export interface TripStoreState
   handleRemoteEvent: (event: WebSocketEvent) => void
   resetTrip: () => void
   loadTrip: (tripId: number | string) => Promise<void>
+  hydrateActiveTrip: (tripId: number | string) => Promise<void>
   refreshDays: (tripId: number | string) => Promise<void>
   updateTrip: (tripId: number | string, data: Partial<Trip>) => Promise<Trip>
   addTag: (data: Partial<Tag> & { name: string }) => Promise<Tag>
@@ -164,6 +165,22 @@ export const useTripStore = create<TripStoreState>((set, get) => ({
     }
   },
 
+  // Silently re-fetch the active trip's collaborative state into the store after
+  // the network comes back (WS reconnect or `online` event) so edits missed while
+  // offline appear in place — no splash, no resetTrip. Each resource is
+  // best-effort; a failure on one must not wipe the others.
+  hydrateActiveTrip: async (tripId: number | string) => {
+    await Promise.all([
+      get().refreshDays(tripId),
+      placeRepo.list(tripId).then(d => set({ places: d.places })).catch(() => {}),
+      packingRepo.list(tripId).then(d => set({ packingItems: d.items })).catch(() => {}),
+      todoRepo.list(tripId).then(d => set({ todoItems: d.items })).catch(() => {}),
+      get().loadBudgetItems(tripId),
+      get().loadReservations(tripId),
+      get().loadFiles(tripId),
+    ])
+  },
+
   refreshDays: async (tripId: number | string) => {
     try {
       const daysData = await dayRepo.list(tripId)