Adds two workflows:
- build-fdroid-debug.yml: builds fdroidDebug variant (no Firebase)
- build-play-debug.yml: builds playDebug variant (with Firebase)
Both run on push/PR to main and upload APK artifacts.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Per project convention, .github/copilot-instructions.md is a pointer,
not a content store. The actual app docs live in AGENTS.md (substantial),
README.md, TESTING.md, and flake.nix.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>