fix: use commit-count based versionCode to prevent downgrade on Firebase

CI_BUILD_ID was using github.run_number which is per-workflow, causing
different workflows to produce different versionCodes (144 vs 9).
Now computed from git commit count + offset, consistent across all workflows.
Also added bundle task to local auto-increment.

.gitignore

@@ -29,6 +29,4 @@ app/*.apk
 google-services.json
 **/google-services.json
 
-# Version properties
-version.properties
 .kotlin/