fix(android): prevent Gradle daemon hang in Firebase test build (#155)

Dagger preserves filesystem snapshots between WithExec steps but kills
background processes. After `flutter build apk --debug` completes, the
Gradle daemon registry file remains in /home/ci/.gradle/daemon/ while
the daemon process itself is gone. The subsequent `./gradlew
app:assembleAndroidTest` step finds the stale registry entry, tries to
connect to the dead daemon, and hangs.

Fix by:
- Adding --no-daemon to the assembleAndroidTest gradlew call so it runs
  in-process and never consults the daemon registry.
- Mounting the gradle-cache volume (same as Base()) so dependencies are
  cached between runs rather than re-downloaded from scratch each time.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ci/main.go

@@ -649,9 +649,12 @@ func (m *Ci) DeployApk(
 // Returns a flat directory with app-debug.apk and app-debug-androidTest.apk.
 func (m *Ci) BuildAndroidDebugApks() *dagger.Directory {
 	built := m.setup(m.firebaseSrc()).
+		WithMountedCache("/home/ci/.gradle", dag.CacheVolume("gradle-cache"), dagger.ContainerWithMountedCacheOpts{Owner: "ci"}).
 		WithExec([]string{"flutter", "build", "apk", "--debug", "--no-pub"}).
 		WithWorkdir("/src/android").
-		WithExec([]string{"./gradlew", "app:assembleAndroidTest"}).
+		// --no-daemon avoids connecting to a stale daemon whose registry file was
+		// preserved in the Dagger layer snapshot but whose process no longer exists.
+		WithExec([]string{"./gradlew", "--no-daemon", "app:assembleAndroidTest"}).
 		WithWorkdir("/src").
 		WithExec([]string{"/bin/bash", "-c",
 			`apk=$(find /src -path "*androidTest*" -name "*.apk" -type f 2>/dev/null | head -1) && \