[Release Track] Android release build and Play setup

[jjoonleo]

Prepare release signing, Firebase config, versioning, signed AAB, Play signing fingerprints, verification, smoke testing, and pre-launch report.

Recommended sub-issue order

1. [Release] Configure release signing ownership and secrets #450 (codex-ready) - [Release] Configure release signing ownership and secrets
2. [Release] Configure release Firebase/Google services file #451 (codex-ready) - [Release] Configure release Firebase/Google services file
3. [Release] Lock initial production versioning #453 (codex-ready) - [Release] Lock initial production versioning
4. [Release] Build a signed release Android App Bundle #452 (blocked) - [Release] Build a signed release Android App Bundle
5. [Release] Verify Play App Signing and certificate fingerprints #454 (blocked) - [Release] Verify Play App Signing and certificate fingerprints
6. [Release] Complete Android developer verification/package registration #455 (manual) - [Release] Complete Android developer verification/package registration
7. [Release] Smoke test release build on Android device #456 (blocked) - [Release] Smoke test release build on Android device
8. [Release] Run Play Console pre-launch report and resolve blockers #459 (manual) - [Release] Run Play Console pre-launch report and resolve blockers

Codex thread guidance

• Take this parent issue as the thread entrypoint.
• Work through sub-issues in the recommended order unless a sub-issue is marked blocked or manual.
• For codex-ready sub-issues, implement or verify only that issue's scope.
• For blocked sub-issues, stop at the prerequisite and leave a status note instead of forcing closure.
• For manual sub-issues, prepare checklist/text/instructions when useful, but do not claim completion without the required human or console access.
• Do not modify issues outside this parent track unless the sub-issue explicitly says to coordinate with them.