Release 1.2.3 (versionCode 6): pin JDK 21 toolchain The app module inherited whichever JDK was on PATH, so bytecode depended on the build host. Pin jvmToolchain(21) to match the engine module and make F-Droid's reproducible-build check deterministic. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>