[codex] Add Play listing graphics checklist

[jjoonleo]

Advances #448.

Parent track: #466.

Summary

• Added a scoped [Release] Prepare Play listing graphics and launcher icon consistency check #448 plan under plans/.
• Added docs/Google-Play-Listing-Graphics.md with current Google Play graphic requirements, launcher-icon consistency checks, and a completion evidence template.
• Linked the graphics checklist from docs/Release-Checklist.md.

Verification

• git diff --check
• git diff --cached --check
• sips -g pixelWidth -g pixelHeight -g hasAlpha assets/icons/app_icon.png web/icons/Icon-512.png web/icons/Icon-192.png android/app/src/main/res/mipmap-mdpi/ic_launcher.png android/app/src/main/res/mipmap-hdpi/ic_launcher.png android/app/src/main/res/mipmap-xhdpi/ic_launcher.png android/app/src/main/res/mipmap-xxhdpi/ic_launcher.png android/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
• Confirmed current Play graphic requirements against official Google Play Console Help pages on 2026-05-10.

Remaining human tasks

• Design/product owner must approve or produce the final Play app icon and feature graphic.
• Release owner must capture final real-app screenshots through [Release] Capture release screenshots from real app screens #449.
• Release owner must compare the uploaded Play app icon against an installed release build launcher icon.
• Release owner must upload approved assets in Play Console and record the design/release asset location.

Track status

• This PR advances the manual [Release] Prepare Play listing graphics and launcher icon consistency check #448 workflow but does not close it because final art approval and Play Console upload require human access.