Add universal reader features: gestures, keyboard, navigator, offline

- gestures.ts: Touch gesture controls (swipe, pinch, tap, double-tap)
- keyboard-shortcuts.ts: Keyboard navigation (arrows, space, page up/down, etc)
- navigator-panel.ts: Affinity-style minimap for page navigation
- offline-manager.ts: Service worker registration and online status
- reading-speed-tracker.ts: Track and sync reading speed to database
- Add web manifest.json for PWA support

web/static/manifest.json

@@ -0,0 +1,22 @@
+{
+  "name": "Bookhoard Reader",
+  "short_name": "Reader",
+  "description": "Offline-capable ebook and comic reader",
+  "start_url": "/dashboard",
+  "display": "fullscreen",
+  "background_color": "#1a1b26",
+  "theme_color": "#1a1b26",
+  "icons": [
+    {
+      "src": "/static/icons/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/static/icons/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ],
+  "offline_enabled": true
+}