fix(build): fail --prod builds with test server defaults; sync web assets before Gradle assembles

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

BUILDING.md

@@ -1176,6 +1176,10 @@ npm run build:ios:prod
     (.../.pkgx/zlib.net/v1.3.0/lib/libz.1.3.dylib) built for 'macOS'` then run
     XCode outside that terminal (ie. not with `npx cap open ios`).
   - Required password entry 26 times.
+  - Before distributing, confirm the archive carries production server
+    defaults. Xcode packages whatever web bundle is in `ios/App/App/public`,
+    even one from a `--test` build:
+    `./scripts/check-prod-bundle.sh ios/App/App/public`
   - Click Distribute -> App Store Connect
 - In AppStoreConnect, add the build to the distribution. You may have to remove
   the current build with the "-" when you hover over it, then "Add Build" with the
@@ -1478,6 +1482,13 @@ cd -
 
 ... and find your `aab` file at app/build/outputs/bundle/release
 
+* Gradle packages whatever web bundle was last synced into
+  `android/app/src/main/assets/public`, even one from a `--test` build. Before
+  uploading, confirm it has production server defaults:
+  `./scripts/check-prod-bundle.sh android/app/build/outputs/bundle/release/app-release.aab`
+* `build-android.sh` runs `./gradlew clean`, which deletes any earlier `aab`, so
+  run `bundleRelease` after the build script finishes.
+
 * Note that F-Droid builds should omit `-PfirebaseEnabled`.
 
 At play.google.com/console:
@@ -2222,6 +2233,8 @@ command chaining, following DRY principles.
 - `7` - Asset generation failed
 - `8` - Android Studio launch failed
 - `9` - Resource check failed
+- `10` - Production bundle has test/dev server defaults (`--prod` only; see
+  `scripts/check-prod-bundle.sh`)
 
 ### A.4 build-ios.sh
 
@@ -2282,6 +2295,8 @@ command chaining, following DRY principles.
 - **Clean Build**: Removes Xcode build artifacts and DerivedData
 - **Asset Generation**: Creates platform-specific assets
 - **Simulator Support**: Launches iOS Simulator for testing
+- **Production Bundle Check**: With `--prod`, exits with code `10` if the synced
+  web bundle has test/dev server defaults (`scripts/check-prod-bundle.sh`)
 
 ### A.5 common.sh