Integrate the Android build fixes with the current release artifact gate, require valid release signing for published APKs, and ignore keystores repository-wide.
Consolidate the duplicate Android build scripts (the legacy one generated a nonexistent lowercase Gradle task name). Fix per-flavor ABI filters so chromeOS builds x86_64 only, move legacy sourceSets to the android extension, and align the compileSdk suppress flag. Repair the malformed JDK/cache step in verify.yml and drop the dead repo gate in android-build.yml. Add release-signing validation with debug-signed warnings, keystore secret wiring plus APK signature checks in release.yml, and update the Android build docs.
Squashed merge of Eden codebase. Original merge had Eden git history
which contained objects incompatible with this repo's remote.
Eden source: https://git.eden-emu.dev/eden-emu/eden