fix(journey): keep page mounted during in-place journey refetch

loadJourney previously set loading=true unconditionally, causing the
JourneyDetailPage guard (if loading || !current) to unmount the entire
page tree on every background refetch — entry saves, settings saves,
trip link/unlink, contributor invite, delete, and WS realtime events
all triggered the full-page spinner flash.

Now loading is only toggled on cold loads (current?.id !== id).
Warm refreshes replace current silently so the hero, sidebar, map,
and timeline stay mounted throughout. Closes #673.

client/src/store/journeyStore.test.ts

@@ -314,6 +314,47 @@ describe('journeyStore', () => {
     expect(storedEntry?.photos[0].id).toBe(201);
   });
 
+  // ── loadJourney silent refresh ───────────────────────────────────────────
+
+  it('FE-STORE-JOURNEY-016: loadJourney does not set loading when refreshing same journey', async () => {
+    const existing = buildJourneyDetail({ id: 5, title: 'Old' });
+    useJourneyStore.setState({ current: existing, loading: false });
+
+    const loadingValues: boolean[] = [];
+    const unsub = useJourneyStore.subscribe(s => loadingValues.push(s.loading));
+
+    const refreshed = buildJourneyDetail({ id: 5, title: 'Refreshed' });
+    server.use(
+      http.get('/api/journeys/5', () => HttpResponse.json(refreshed))
+    );
+
+    await useJourneyStore.getState().loadJourney(5);
+    unsub();
+
+    expect(loadingValues.every(v => v === false)).toBe(true);
+    expect(useJourneyStore.getState().current?.title).toBe('Refreshed');
+  });
+
+  it('FE-STORE-JOURNEY-017: loadJourney sets loading on cold load (different journey)', async () => {
+    const existing = buildJourneyDetail({ id: 5 });
+    useJourneyStore.setState({ current: existing, loading: false });
+
+    const loadingValues: boolean[] = [];
+    const unsub = useJourneyStore.subscribe(s => loadingValues.push(s.loading));
+
+    const other = buildJourneyDetail({ id: 99 });
+    server.use(
+      http.get('/api/journeys/99', () => HttpResponse.json(other))
+    );
+
+    await useJourneyStore.getState().loadJourney(99);
+    unsub();
+
+    expect(loadingValues).toContain(true);
+    expect(useJourneyStore.getState().current?.id).toBe(99);
+    expect(useJourneyStore.getState().loading).toBe(false);
+  });
+
   // ── clear ────────────────────────────────────────────────────────────────
 
   it('FE-STORE-JOURNEY-015: clear resets state', () => {

client/src/store/journeyStore.ts

@@ -124,7 +124,8 @@ export const useJourneyStore = create<JourneyState>((set, get) => ({
   },
 
   loadJourney: async (id) => {
-    set({ loading: true, notFound: false })
+    const cold = get().current?.id !== id
+    if (cold) set({ loading: true, notFound: false })
     try {
       const data = await journeyApi.get(id)
       set({ current: data })
@@ -134,7 +135,7 @@ export const useJourneyStore = create<JourneyState>((set, get) => ({
       }
       throw err
     } finally {
-      set({ loading: false })
+      if (cold) set({ loading: false })
     }
   },