feat: Memories tab — slideshow of photos on this day with ambient music

- New /api/memories/today endpoint queries photos by month+day (client
  sends its local date to avoid UTC offset issues in Docker)
- MemoriesView shows photos grouped by year with a "Play Memories"
  slideshow that crossfades between photos every 5 seconds
- Ambient music generated via Web Audio API — A-minor pad with slow
  vibrato shimmer and a pentatonic melody with convolver reverb
- Mute toggle, keyboard nav (← → Esc), progress dots, year badge
- fix: map popup images now use explicit px dimensions (100% was
  collapsing to 0 inside Leaflet's unsized popup content box)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/src/App.jsx

@@ -8,7 +8,8 @@ import DuplicatesView from './components/DuplicatesView.jsx';
 import SettingsPanel from './components/SettingsPanel.jsx';
 
 import { lazy, Suspense } from 'react';
-const MapView = lazy(() => import('./components/MapView.jsx'));
+const MapView      = lazy(() => import('./components/MapView.jsx'));
+const MemoriesView = lazy(() => import('./components/MemoriesView.jsx'));
 
 const EMPTY_FILTERS = { q: '', from: '', to: '', tagId: '', collectionId: '', starred: '', city: '' };
 const SIDEBAR_W = 210;
@@ -125,6 +126,7 @@ export default function App() {
               </span>
             )}
           </Tab>
+          <Tab active={view === 'memories'}   onClick={() => setView('memories')}>Memories</Tab>
           <Tab active={view === 'map'}        onClick={() => setView('map')}>Map</Tab>
           <Tab active={view === 'duplicates'} onClick={() => setView('duplicates')}>
             Duplicates
@@ -214,6 +216,13 @@ export default function App() {
             </>
           )}
 
+          {/* Memories */}
+          {view === 'memories' && (
+            <Suspense fallback={<p style={{ padding: 24, color: '#777', fontSize: 13 }}>Loading…</p>}>
+              <MemoriesView />
+            </Suspense>
+          )}
+
           {/* Map */}
           {view === 'map' && (
             <Suspense fallback={<p style={{ padding: 24, color: '#777', fontSize: 13 }}>Loading map…</p>}>