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/routes/public.rs

@@ -43,7 +43,11 @@ pub async fn manifest(State(state): State<AppState>, MaybeUser(user): MaybeUser)
     }))
 }
 
-pub async fn instance_manifest(State(state): State<AppState>, MaybeUser(user): MaybeUser, Path(id): Path<String>) -> AppResult<Json<InstanceManifest>> {
+pub async fn instance_manifest(
+    State(state): State<AppState>,
+    MaybeUser(user): MaybeUser,
+    Path(id): Path<String>,
+) -> AppResult<Json<InstanceManifest>> {
     let row = store::get_instance(&state, &id).await?;
     let groups = match &user {
         Some(u) => auth::user_groups(&state, u.id).await?,
@@ -120,7 +124,11 @@ pub async fn me(State(state): State<AppState>, AuthUser(user): AuthUser) -> AppR
     Ok(Json(auth::public_user(&state, &user).await?))
 }
 
-pub async fn event(State(state): State<AppState>, MaybeUser(user): MaybeUser, Json(ev): Json<LaunchEvent>) -> AppResult<Json<serde_json::Value>> {
+pub async fn event(
+    State(state): State<AppState>,
+    MaybeUser(user): MaybeUser,
+    Json(ev): Json<LaunchEvent>,
+) -> AppResult<Json<serde_json::Value>> {
     let kind = if ev.kind == "launch" { "launch" } else { "other" };
     let name = user.map(|u| u.username).or(ev.username).map(|n| n.chars().take(32).collect::<String>());
     sqlx::query("INSERT INTO events (instance_id, username, kind, created_at) VALUES (?, ?, ?, ?)")