[Release] Build a signed release Android App Bundle

[jjoonleo]

Backlog ID: ISSUE-020
Source: plans/release_app_todos.md

Goal

Produce the upload artifact for Play Console.

Parallelization

Status: blocked

Prerequisites

• [Release] Configure release signing ownership and secrets #450 - Release signing inputs must be configured.
• [Release] Configure release Firebase/Google services file #451 - Release Firebase/Google services config must be available.
• [Release] Lock initial production versioning #453 - Initial production versioning must be locked.

Acceptance criteria

• flutter pub get succeeds.
• dart run build_runner build --delete-conflicting-outputs succeeds if generated files need refresh.
• flutter analyze succeeds or known release-blocking findings are fixed.
• flutter test succeeds or failures are triaged.
• flutter build appbundle --release succeeds with release signing and Firebase config.
• Artifact path is recorded.

Codex thread guidance

• Work only on this issue's scope.
• Do not modify unrelated release issues.
• If this issue is blocked by external access or human approval, prepare the needed checklist/text and leave the issue open.
• Do not implement final closure until the prerequisites above are complete; prepare only unblocker notes if started early.