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/auth.rs

@@ -90,12 +90,10 @@ impl UserRow {
 }
 
 pub async fn user_groups(state: &AppState, user_id: i64) -> AppResult<Vec<String>> {
-    Ok(sqlx::query_scalar(
-        "SELECT g.name FROM groups g JOIN user_groups ug ON ug.group_id = g.id WHERE ug.user_id = ? ORDER BY g.name",
-    )
-    .bind(user_id)
-    .fetch_all(&state.db)
-    .await?)
+    Ok(sqlx::query_scalar("SELECT g.name FROM groups g JOIN user_groups ug ON ug.group_id = g.id WHERE ug.user_id = ? ORDER BY g.name")
+        .bind(user_id)
+        .fetch_all(&state.db)
+        .await?)
 }
 
 pub async fn public_user(state: &AppState, user: &UserRow) -> AppResult<PublicUser> {