Add admin system, registration gate, mudtool database editor, and test checklist

- Add is_admin flag to player DB schema with migration for existing databases
- Add server_settings table for key-value config (registration_open, etc.)
- Add 10 in-game admin commands: promote, demote, kick, teleport, registration,
  announce, heal, info, setattitude, list — all gated behind admin flag
- Registration gate: new players rejected when registration_open=false,
  existing players can still reconnect
- Add mudtool binary with CLI mode (players/settings/attitudes CRUD) and
  interactive ratatui TUI with tabbed interface for database management
- Restructure to lib.rs + main.rs so mudtool shares DB code with server
- Add TESTING.md with comprehensive pre-commit checklist and smoke test script
- Stats and who commands show [ADMIN] badge; help shows admin section for admins

Made-with: Cursor

src/main.rs

@@ -1,12 +1,3 @@
-mod ansi;
-mod chargen;
-mod combat;
-mod commands;
-mod db;
-mod game;
-mod ssh;
-mod world;
-
 use std::path::PathBuf;
 use std::sync::Arc;
 use tokio::sync::Mutex;
@@ -15,6 +6,11 @@ use russh::keys::ssh_key::rand_core::OsRng;
 use russh::server::Server as _;
 use tokio::net::TcpListener;
 
+use mudserver::db;
+use mudserver::game;
+use mudserver::ssh;
+use mudserver::world;
+
 const DEFAULT_PORT: u16 = 2222;
 const DEFAULT_WORLD_DIR: &str = "./world";
 const DEFAULT_DB_PATH: &str = "./mudserver.db";
@@ -33,7 +29,10 @@ async fn main() {
         match args[i].as_str() {
             "--port" | "-p" => {
                 i += 1;
-                port = args.get(i).and_then(|s| s.parse().ok()).expect("--port requires a number");
+                port = args
+                    .get(i)
+                    .and_then(|s| s.parse().ok())
+                    .expect("--port requires a number");
             }
             "--world" | "-w" => {
                 i += 1;
@@ -71,7 +70,8 @@ async fn main() {
     });
     let db: Arc<dyn db::GameDb> = Arc::new(database);
 
-    let key = russh::keys::PrivateKey::random(&mut OsRng, russh::keys::Algorithm::Ed25519).unwrap();
+    let key =
+        russh::keys::PrivateKey::random(&mut OsRng, russh::keys::Algorithm::Ed25519).unwrap();
     let config = russh::server::Config {
         inactivity_timeout: Some(std::time::Duration::from_secs(3600)),
         auth_rejection_time: std::time::Duration::from_secs(1),