feat: Add mobile CI/CD secrets setup for APK signing

- Updated Makefile to include new command for setting up mobile CI secrets.
- Enhanced tools.mk with setup-mobile-ci-secrets target.
- Created setup-mobile-github-secrets.sh script for configuring GitHub Secrets for APK signing.
- Added APK signing implementation summary documentation.
- Created detailed APK signing setup guide.
- Added GitHub secrets checklist for easy reference.

makefiles/tools.mk

@@ -1,6 +1,6 @@
 # --- Development Tools ---
 
-.PHONY: install-git-hooks sync-prototypes install-melos clean-branches
+.PHONY: install-git-hooks sync-prototypes install-melos clean-branches setup-mobile-ci-secrets
 
 install-melos:
 	@if ! command -v melos >/dev/null 2>&1; then \
@@ -54,3 +54,8 @@ clean-branches:
 		fi; \
 	done; \
 	echo "\n✅ Done! Deleted $$DELETED branch(es), skipped $$SKIPPED protected branch(es)."
+
+setup-mobile-ci-secrets:
+	@echo "--> Running GitHub Secrets setup helper for APK signing..."
+	@./.github/scripts/setup-mobile-github-secrets.sh
+	@echo "\n📚 For more information, see: docs/RELEASE/APK_SIGNING_SETUP.md"