feat: add config, auth, fetcher, java modules
- config: OS-specific paths, launcher.json load/save, DefaultSettings with MRIXSCRAFT_SERVER_URL env override
- auth: Yggdrasil client (authenticate, refresh, validate), session persistence in session.json, EnsureValid flow
- fetcher: HTTP download with SHA-1 verification, WorkerPool for concurrent downloads
- java: JRE detection (IsInstalled/Find), platform-specific executable name
- utils: SHA1File, SHA1Bytes, Unzip with zip-slip protection
- cmd/launcher: wire config + auth into main, session restore on startup
Co-Authored-By: OWL <noreply@anthropic.com>
Vladimir Zagainov
070b5c0262