Panel: Yggdrasil auth server (authlib-injector), skins and capes

- Yggdrasil API per the authlib-injector spec: metadata with signing key
  and skin domains, authenticate/refresh/validate/invalidate/signout,
  join/hasJoined, profile lookup, texture upload, and the minecraftservices
  endpoints (chat certificates, publickeys, attributes, blocklist)
- 4096-bit signing key generated once into the data volume; textures and
  chat certificates signed SHA1withRSA (verified with Java's own crypto)
- Skins/capes stored content-addressed after validation and re-encoding;
  cape library with public/group/private visibility; head avatars API
- Launcher login returns a game session; launcher sessions recorded for
  launcher-only servers; authlib-injector download mirror
- Schema v2: player UUIDs (offline UUID backfilled), skins, capes, tokens,
  sessions, chat keys, game server tables
- Remove Microsoft sign-in from the engine and panel

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

panel/server/src/main.rs

@@ -25,7 +25,9 @@ async fn main() -> anyhow::Result<()> {
 
     let listener = tokio::net::TcpListener::bind(&bind).await?;
     tracing::info!("SCOPENET panel v{} listening on http://{bind}", env!("CARGO_PKG_VERSION"));
-    axum::serve(listener, app(state)).with_graceful_shutdown(shutdown()).await?;
+    axum::serve(listener, app(state).into_make_service_with_connect_info::<std::net::SocketAddr>())
+        .with_graceful_shutdown(shutdown())
+        .await?;
     Ok(())
 }