Migrate from .NET MAUI to Expo + Convex

Complete rewrite of Scry using TypeScript stack:

- Expo/React Native with Expo Router (file-based routing)
- Convex backend (serverless functions + real-time database)
- Adaptive camera system (expo-camera in Expo Go, Vision Camera in production)
- React Native Skia + fast-opencv for image processing
- GDPR-compliant auth setup with Zitadel OIDC (pending configuration)

Key features:
- Card recognition pipeline ported to TypeScript
- Perceptual hashing (192-bit color pHash)
- CLAHE preprocessing for lighting normalization
- Local SQLite cache with Convex sync
- Collection management with offline support

Removes all .NET/MAUI code (src/, test/, tools/).

💘 Generated with Crush

Assisted-by: Claude Opus 4.5 via Crush <crush@charm.land>

lib/db/index.ts

@@ -0,0 +1,20 @@
+/**
+ * Local database module exports.
+ */
+
+export {
+  initDatabase,
+  getLastSyncTimestamp,
+  setLastSyncTimestamp,
+  getCachedHashes,
+  getCachedCardCount,
+  upsertCards,
+  clearCache,
+  closeDatabase,
+} from "./localDatabase";
+
+export {
+  createSyncService,
+  type SyncService,
+  type SyncStatus,
+} from "./syncService";