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

crates/core/src/ping.rs

@@ -231,7 +231,8 @@ mod tests {
 
     #[test]
     fn flattens_motd() {
-        let v: serde_json::Value = serde_json::from_str(r#"{"text":"","extra":[{"text":"Scope","color":"aqua","bold":true},{"text":"Net"}]}"#).unwrap();
+        let v: serde_json::Value =
+            serde_json::from_str(r#"{"text":"","extra":[{"text":"Scope","color":"aqua","bold":true},{"text":"Net"}]}"#).unwrap();
         assert_eq!(flatten_chat(&v), "§b§lScope§rNet");
         assert_eq!(flatten_chat(&serde_json::json!("§aHello")), "§aHello");
     }