Fixed workflow failure by ensuring only data goes to stdout, not informational messages. Also added support for version format X.Y.Z-suffix in addition to X.Y.Z+build.
Add four new helper scripts for mobile APK workflows: setup-apk-signing.sh (decode keystores and export signing env vars), verify-apk-signature.sh (check and display APK certificate info), attach-apk-to-release.sh (rename and upload APK to a GitHub Release), and setup-mobile-github-secrets.sh (helper to generate/show required GitHub Secrets). Update product-release.yml to expose version/tag outputs and add a build-mobile-artifacts job that sets up Java/Flutter, installs deps, configures signing from repository secrets, builds APKs for worker/client apps, verifies signatures, uploads artifacts, and optionally attaches the APK to the GitHub Release. Secrets and envvar naming conventions are handled to support dev/staging/prod keystores; documentation references (docs/RELEASE/APK_SIGNING_SETUP.md) are noted in scripts.
