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>

components/camera/ExpoCamera.tsx

@@ -0,0 +1,48 @@
+/**
+ * Camera component using expo-camera (works in Expo Go).
+ */
+
+import React, { forwardRef, useImperativeHandle, useRef } from "react";
+import { StyleSheet } from "react-native";
+import { CameraView } from "expo-camera";
+
+export interface CameraHandle {
+  takePhoto: () => Promise<{ uri: string }>;
+}
+
+interface ExpoCameraProps {
+  flashEnabled?: boolean;
+}
+
+export const ExpoCamera = forwardRef<CameraHandle, ExpoCameraProps>(
+  ({ flashEnabled = false }, ref) => {
+    const cameraRef = useRef<CameraView>(null);
+
+    useImperativeHandle(ref, () => ({
+      takePhoto: async () => {
+        if (!cameraRef.current) {
+          throw new Error("Camera not ready");
+        }
+        const photo = await cameraRef.current.takePictureAsync({
+          quality: 0.8,
+          base64: false,
+        });
+        if (!photo) {
+          throw new Error("Failed to capture photo");
+        }
+        return { uri: photo.uri };
+      },
+    }));
+
+    return (
+      <CameraView
+        ref={cameraRef}
+        style={StyleSheet.absoluteFill}
+        facing="back"
+        flash={flashEnabled ? "on" : "off"}
+      />
+    );
+  }
+);
+
+ExpoCamera.displayName = "ExpoCamera";

components/camera/VisionCamera.tsx

@@ -0,0 +1,53 @@
+/**
+ * Camera component using react-native-vision-camera (production builds).
+ */
+
+import React, { forwardRef, useImperativeHandle, useRef } from "react";
+import { StyleSheet } from "react-native";
+import { Camera, useCameraDevice } from "react-native-vision-camera";
+
+export interface CameraHandle {
+  takePhoto: () => Promise<{ uri: string }>;
+}
+
+interface VisionCameraProps {
+  flashEnabled?: boolean;
+}
+
+export const VisionCamera = forwardRef<CameraHandle, VisionCameraProps>(
+  ({ flashEnabled = false }, ref) => {
+    const device = useCameraDevice("back");
+    const cameraRef = useRef<Camera>(null);
+
+    useImperativeHandle(ref, () => ({
+      takePhoto: async () => {
+        if (!cameraRef.current) {
+          throw new Error("Camera not ready");
+        }
+        const photo = await cameraRef.current.takePhoto({
+          flash: flashEnabled ? "on" : "off",
+          enableShutterSound: false,
+        });
+        return { uri: photo.path };
+      },
+    }));
+
+    if (!device) {
+      return null;
+    }
+
+    return (
+      <Camera
+        ref={cameraRef}
+        style={StyleSheet.absoluteFill}
+        device={device}
+        isActive={true}
+        photo={true}
+      />
+    );
+  }
+);
+
+VisionCamera.displayName = "VisionCamera";
+
+export { useCameraDevice };

components/camera/index.tsx

@@ -0,0 +1,64 @@
+/**
+ * Adaptive camera component that uses expo-camera in Expo Go
+ * and react-native-vision-camera in production builds.
+ */
+
+import React, { forwardRef, lazy, Suspense } from "react";
+import { View, ActivityIndicator, StyleSheet, Text } from "react-native";
+import Constants from "expo-constants";
+
+export interface CameraHandle {
+  takePhoto: () => Promise<{ uri: string }>;
+}
+
+interface AdaptiveCameraProps {
+  flashEnabled?: boolean;
+}
+
+// Detect if running in Expo Go
+const isExpoGo = Constants.appOwnership === "expo";
+
+// Lazy load the appropriate camera component
+const ExpoCamera = lazy(() =>
+  import("./ExpoCamera").then((m) => ({ default: m.ExpoCamera }))
+);
+const VisionCamera = lazy(() =>
+  import("./VisionCamera").then((m) => ({ default: m.VisionCamera }))
+);
+
+const CameraLoading = () => (
+  <View style={styles.loading}>
+    <ActivityIndicator size="large" color="#007AFF" />
+    <Text style={styles.loadingText}>Initializing camera...</Text>
+  </View>
+);
+
+export const AdaptiveCamera = forwardRef<CameraHandle, AdaptiveCameraProps>(
+  (props, ref) => {
+    const CameraComponent = isExpoGo ? ExpoCamera : VisionCamera;
+
+    return (
+      <Suspense fallback={<CameraLoading />}>
+        <CameraComponent ref={ref} {...props} />
+      </Suspense>
+    );
+  }
+);
+
+AdaptiveCamera.displayName = "AdaptiveCamera";
+
+const styles = StyleSheet.create({
+  loading: {
+    ...StyleSheet.absoluteFillObject,
+    backgroundColor: "#000",
+    justifyContent: "center",
+    alignItems: "center",
+  },
+  loadingText: {
+    marginTop: 16,
+    color: "#888",
+    fontSize: 14,
+  },
+});
+
+export { isExpoGo };