Republish setup: fastlane + Forgejo CI, signing/version fixes, Play-policy link

- support_page: repoint comunes.org link to project page (Play re-approval)
- build.gradle: conditional release signing (debug fallback), versionCode/Name
  from pubspec, drop duplicate google-services plugin
- pubspec: version 1.10.0+10 (versionCode must exceed last uploaded)
- track AndroidManifest.xml (no secrets in it)
- fastlane: Appfile/Fastfile (deploy_play/deploy_metadata/promote_production) +
  Gemfile + es/en/gl store metadata
- .forgejo: ci.yml (analyze+test) + release.yml (tag v* -> signed AAB -> Play internal)
- README + RELEASE.md

README.md

@@ -22,14 +22,21 @@ also you can run with `watch` instead of `build` to build with any code change.
 
 Generate apk with:
 ```
-flutter build apk -t lib/mainProd.dart --flavor production
+flutter build apk --release -t lib/main_prod.dart --flavor production
 ```
-also you can run with `-t lib/mainDev.dart --flavor development`. More info about flavors [here](https://medium.com/@salvatoregiordanoo/flavoring-flutter-392aaa875f36).
+also you can run with `-t lib/main_dev.dart --flavor development`. More info about flavors [here](https://medium.com/@salvatoregiordanoo/flavoring-flutter-392aaa875f36).
 
 ## Testing
 
 Run `flutter test` for doing unit testing.
 
+## Release
+
+Publishing to Google Play is automated and password-free via Forgejo Actions on
+`git.comunes.org`. See [RELEASE.md](RELEASE.md). TL;DR: bump `version:` in
+`pubspec.yaml`, then `git tag vX.Y && git push origin vX.Y` — CI builds a signed
+AAB and uploads it to the Play *internal* track.
+
 ## Data source acknowledgements
 
 *We acknowledge the use of data and imagery from LANCE FIRMS operated by the NASA/GSFC/Earth Science Data and Information System (ESDIS) with funding provided by NASA/HQ*.