Add launcher engine (scopenet-core) and admin panel server

- scopenet-shared: wire types for branding, auth, instances, manifests
- scopenet-core: Mojang versions/libraries/assets, automatic Java runtimes,
  Fabric/Quilt/Forge/NeoForge installation, file sync, launch command
  builder, Microsoft auth, servers.dat injection, server list ping
- scopenet-panel: Axum + SQLite admin API with JWT auth, users/groups,
  branding, settings, instances, Modrinth/CurseForge/zip import, file
  hosting and launch stats

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

panel/server/src/state.rs

@@ -0,0 +1,13 @@
+use crate::auth::{Keys, LoginGuard};
+use crate::config::Config;
+use sqlx::SqlitePool;
+use std::sync::Arc;
+
+#[derive(Clone)]
+pub struct AppState {
+    pub db: SqlitePool,
+    pub cfg: Arc<Config>,
+    pub keys: Arc<Keys>,
+    pub http: reqwest::Client,
+    pub login_guard: Arc<LoginGuard>,
+}