Add Docker image, Compose, CI/CD workflows and docs

- Multi-arch (amd64/arm64) panel image: static musl binary on scratch,
  cross-compiled with cargo-zigbuild (no QEMU), non-root, healthcheck
- docker-compose.yml + .env.example for one-command deployment
- CI: fmt, clippy, tests, web type-checks, Windows launcher build,
  real-network installs of vanilla/Fabric/Quilt/Forge/NeoForge,
  Docker build
- Release: Windows NSIS installer with baked-in panel URL, GHCR image
  push and GitHub release (tag push or manual dispatch)
- README, admin guide, Microsoft auth setup, architecture, development
- rustfmt config and formatting pass

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

panel/server/src/lib.rs

@@ -89,10 +89,7 @@ pub fn app(state: AppState) -> Router {
         .route("/healthz", axum::routing::get(routes::public::health))
         .merge(routes::api(&state))
         .nest_service("/files", ServeDir::new(state.cfg.files_dir()))
-        .nest_service(
-            "/uploads",
-            tower::ServiceBuilder::new().layer(long_cache).service(ServeDir::new(state.cfg.uploads_dir())),
-        )
+        .nest_service("/uploads", tower::ServiceBuilder::new().layer(long_cache).service(ServeDir::new(state.cfg.uploads_dir())))
         .fallback_service(spa)
         .layer(CompressionLayer::new())
         .layer(TraceLayer::new_for_http())