feat: video support + Memories music choices

Videos:
- Worker ingests .mp4 .mov .m4v .avi .mkv .webm .3gp via ffmpeg/ffprobe
  (frame extract → sharp resize, same thumbnail pipeline as photos)
- DB: media_type + duration columns with migration
- GET /api/videos returns all indexed videos
- GET /api/photos/:id/video streams original file with Range support
  for browser seek/scrub
- VideosView: 16:9 thumbnail grid, play-button overlay, duration badge
- Full-screen player: native <video controls>, ESC to close
- Library tab now excludes videos (dedicated Videos tab)
- Dockerfile: adds ffmpeg to runtime stage

Memories music choices:
- Three styles: ⚡ Upbeat (G-major, default), 🌙 Dreamy (A-minor),
  🎬 Cinematic (D-minor, dual-oscillator richness)
- Shared Web Audio engine (reverb, LPF, pad + melody)
- Style picker in header; active style icon shown in slideshow bar

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

client/src/App.jsx

@@ -10,6 +10,7 @@ import SettingsPanel from './components/SettingsPanel.jsx';
 import { lazy, Suspense } from 'react';
 const MapView      = lazy(() => import('./components/MapView.jsx'));
 const MemoriesView = lazy(() => import('./components/MemoriesView.jsx'));
+const VideosView   = lazy(() => import('./components/VideosView.jsx'));
 
 const EMPTY_FILTERS = { q: '', from: '', to: '', tagId: '', collectionId: '', starred: '', city: '' };
 const SIDEBAR_W = 210;
@@ -126,6 +127,7 @@ export default function App() {
               </span>
             )}
           </Tab>
+          <Tab active={view === 'videos'}     onClick={() => setView('videos')}>Videos</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')}>
@@ -216,6 +218,13 @@ export default function App() {
             </>
           )}
 
+          {/* Videos */}
+          {view === 'videos' && (
+            <Suspense fallback={<p style={{ padding: 24, color: '#777', fontSize: 13 }}>Loading…</p>}>
+              <VideosView />
+            </Suspense>
+          )}
+
           {/* Memories */}
           {view === 'memories' && (
             <Suspense fallback={<p style={{ padding: 24, color: '#777', fontSize: 13 }}>Loading…</p>}>