[Release] Create reusable app release checklist

[jjoonleo]

Backlog ID: ISSUE-030
Source: plans/release_app_todos.md

Goal

Make future releases repeatable.

Parallelization

Status: blocked

Prerequisites

• [Release] Configure release signing ownership and secrets #450-[Release] Run Play Console pre-launch report and resolve blockers #459 - Release flow, build, QA, and Play Console steps must settle enough to document the actual checklist.

Acceptance criteria

• Checklist covers generated files, analysis, tests, version bump, release signing, Firebase config, AAB build, Data safety/privacy changes, screenshots, Play declarations, and rollout monitoring.
• Include commands: flutter analyze, flutter test, dart run build_runner build --delete-conflicting-outputs, and flutter build appbundle --release.
• Checklist defines what changes require privacy policy or Data safety updates.
• Checklist is stored in docs/ or plans/ as agreed by the team.

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.