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/store.rs

@@ -193,12 +193,11 @@ pub struct FileStats {
 }
 
 pub async fn file_stats(state: &AppState, instance_id: &str) -> AppResult<FileStats> {
-    let (count, size, missing): (i64, Option<i64>, Option<i64>) = sqlx::query_as(
-        "SELECT COUNT(*), SUM(size), SUM(CASE WHEN url = '' THEN 1 ELSE 0 END) FROM instance_files WHERE instance_id = ?",
-    )
-    .bind(instance_id)
-    .fetch_one(&state.db)
-    .await?;
+    let (count, size, missing): (i64, Option<i64>, Option<i64>) =
+        sqlx::query_as("SELECT COUNT(*), SUM(size), SUM(CASE WHEN url = '' THEN 1 ELSE 0 END) FROM instance_files WHERE instance_id = ?")
+            .bind(instance_id)
+            .fetch_one(&state.db)
+            .await?;
     Ok(FileStats { count: count as u32, size: size.unwrap_or(0) as u64, missing: missing.unwrap_or(0) as u32 })
 }