F-095: progressive example Metro DI (11-metro-di)

[stepango]

Summary

• Add examples/android/11-metro-di teaching Metro (dev.zacsweers.metro 1.3.2) as a type-owned external plugin.
• Path A: register Metro once on impl + app; thin metroImpl / metroApp DSLs keep call sites attributes-only.
• Mini DI: @Inject feature impl + @DependencyGraph / createGraph at composition root.
• Ladder docs + agent skill pointers; JVM 11 for Metro runtime.

Verify

source scripts/env-mac.sh
printf 'sdk.dir=%s\n' \"$ANDROID_HOME\" > examples/android/11-metro-di/local.properties
cd examples/android/11-metro-di && ./gradlew :binary:assembleDebug
# Metro tasks present on :root-app
./gradlew :root-app:tasks --all | grep -i metro

Host: BUILD SUCCESSFUL (debug APK produced).

Ticket

F-095 → done