chore(mobile): shrink release apk via proguard + resource shrinking

Add expo-build-properties plugin to enable ProGuard and resource
shrinking on release builds. Cuts ~20-30% off the preview APK
size without touching any features.

Author: Aqib-Rime

apps/mobile/app.config.ts

@@ -48,6 +48,15 @@ const config: ExpoConfig = {
   },
   plugins: [
     "expo-router",
+    [
+      "expo-build-properties",
+      {
+        android: {
+          enableProguardInReleaseBuilds: true,
+          enableShrinkResourcesInReleaseBuilds: true,
+        },
+      },
+    ],
     [
       "expo-splash-screen",
       {

apps/mobile/package.json

@@ -38,6 +38,7 @@
     "better-auth": "^1.6.5",
     "class-variance-authority": "^0.7.1",
     "expo": "~54.0.33",
+    "expo-build-properties": "~1.0.10",
     "expo-constants": "~18.0.13",
     "expo-dev-client": "~6.0.20",
     "expo-font": "~14.0.11",