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>

.just/emu.just

@@ -0,0 +1,35 @@
+set shell := ["C:/Program Files/Git/usr/bin/bash.exe", "-c"]
+set unstable := true
+
+android_sdk := replace(env('LOCALAPPDATA'), '\', '/') / "Android/Sdk"
+adb := android_sdk / "platform-tools/adb.exe"
+avd := android_sdk / "cmdline-tools/latest/bin/avdmanager.bat"
+emulator := android_sdk / "emulator/emulator.exe"
+camera_virtual := "-camera-back virtualscene -virtualscene-poster wall=\"" + (justfile_directory() / "TestImages/reference_alpha/serra_angel.jpg") + "\""
+camera_webcam := "-camera-back webcam0 -camera-front webcam0"
+
+default camera="virtual":
+    {{ emulator }} -avd Pixel_6 {{ if camera == "virtual" { camera_virtual } else { camera_webcam } }} -no-snapshot-load -gpu host
+
+install:
+    {{ avd }} delete avd -n Pixel_6
+    {{ avd }} create avd -n Pixel_6 -k "system-images;android-36;google_apis_playstore;x86_64" -d pixel_6
+
+# Wait for emulator to fully boot (timeout after 2 minutes)
+[script]
+emu-wait:
+    # Wait for Android emulator to boot with timeout
+    TIMEOUT=120
+
+    echo "Waiting for emulator to boot..."
+
+    for ((i=TIMEOUT; i>0; i--)); do
+        if [ "$({{ adb }} shell getprop sys.boot_completed 2>/dev/null)" = "1" ]; then
+            echo "Emulator ready"
+            exit 0
+        fi
+        sleep 1
+    done
+
+    echo "Emulator failed to boot within 2 minutes"
+    exit 1