v0.1.1 — managed Java 17 runtime

Launcher now resolves its own jar directory and manages a Java 17 runtime in javahome/ (auto-downloads Temurin JRE 17 for macOS/Linux/Windows, x64 + ARM64 where available). Minecraft always launches on the managed Java 17 — newer system JDKs (e.g. Java 26 / class version 70) can no longer break Fabric. Default game dir moved to /luamap-run. Run: java -jar luamap-launcher.jar (or --server for headless).