Enable EAS remote build caching

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -38,6 +38,11 @@ server and open the app on your device or simulator:
 
     npm run start
 
+Remote build caching is enabled (`buildCacheProvider` in `app.json`): when you're logged in
+to EAS (`npx eas-cli login`) and a member of the `neuf` organization, `npm run android`/`ios`
+download a cached build if the native fingerprint is unchanged, and upload new local builds
+for others to reuse. Without a login they just build locally.
+
 ### Demo users
 
 Dev builds accept three fake users (defined in `src/api.ts`) so you can preview the
@@ -114,9 +119,6 @@ history, code and binary blobs related to React Native functionality filtered ou
   - add an iOS 26 liquid glass icon: a `.icon` file made with Apple's Icon Composer,
     referenced from `ios.icon` (old icon remains as fallback for older iOS); optionally
     play with [`expo-glass-effect`](https://docs.expo.dev/versions/latest/sdk/glass-effect/)
-  - consider [remote build caching](https://docs.expo.dev/guides/cache-builds-remotely/)
-    (now stable) so `npm run android`/`ios` can download a cached build instead of
-    compiling locally when the native fingerprint is unchanged
   - try [`@expo/ui`](https://docs.expo.dev/versions/latest/sdk/ui/), production-ready as of SDK 56:
     real SwiftUI / Jetpack Compose components that could back the homegrown ones in
     `src/components/`

app.json

@@ -79,6 +79,7 @@
       }
     },
     "owner": "neuf",
+    "buildCacheProvider": "eas",
     "experiments": {
       "reactCompiler": true
     }

package.json

@@ -55,6 +55,7 @@
     "@testing-library/react-native": "^14.0.1",
     "@types/jest": "^29.5.14",
     "@types/react": "~19.2.10",
+    "eas-build-cache-provider": "^25.3.0",
     "eslint": "^9.39.5",
     "eslint-config-expo": "~57.0.2",
     "eslint-config-prettier": "^10.1.8",