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>

convex/scanHistory.ts

@@ -0,0 +1,58 @@
+import { v } from "convex/values";
+import { query, mutation } from "./_generated/server";
+
+// Get recent scan history
+export const getRecent = query({
+  args: { userId: v.id("users"), limit: v.optional(v.number()) },
+  handler: async (ctx, { userId, limit = 50 }) => {
+    const history = await ctx.db
+      .query("scanHistory")
+      .withIndex("by_user", (q) => q.eq("userId", userId))
+      .order("desc")
+      .take(limit);
+
+    // Enrich with card data
+    const enriched = await Promise.all(
+      history.map(async (entry) => {
+        const card = entry.cardId ? await ctx.db.get(entry.cardId) : null;
+        return {
+          ...entry,
+          card,
+        };
+      })
+    );
+
+    return enriched;
+  },
+});
+
+// Record a scan
+export const record = mutation({
+  args: {
+    userId: v.id("users"),
+    cardId: v.optional(v.id("cards")),
+    confidence: v.number(),
+    addedToCollection: v.boolean(),
+  },
+  handler: async (ctx, args) => {
+    return await ctx.db.insert("scanHistory", {
+      ...args,
+      scannedAt: Date.now(),
+    });
+  },
+});
+
+// Clear scan history
+export const clear = mutation({
+  args: { userId: v.id("users") },
+  handler: async (ctx, { userId }) => {
+    const entries = await ctx.db
+      .query("scanHistory")
+      .withIndex("by_user", (q) => q.eq("userId", userId))
+      .collect();
+
+    for (const entry of entries) {
+      await ctx.db.delete(entry._id);
+    }
+  },
+});