fix: respawn disabled state not persisted across server restarts

When /respawn/stop was called, the controller was stopped but remained
in the respawnControllers map. This caused persistSessionState() to
still read config.enabled=true and save respawnEnabled=true to state.json.

On server restart, the respawn controller would be re-enabled because
state.json had respawnEnabled=true.

Fix: Remove controller from map and clear any timed respawn when
/respawn/stop is called, so persistSessionState() correctly sets
respawnEnabled=false.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/server.ts

@@ -790,6 +790,16 @@ export class WebServer extends EventEmitter {
 
       controller.stop();
 
+      // Remove controller from map so persistSessionState doesn't save respawnEnabled: true
+      this.respawnControllers.delete(id);
+
+      // Clear any timed respawn
+      const timerInfo = this.respawnTimers.get(id);
+      if (timerInfo) {
+        clearTimeout(timerInfo.timer);
+        this.respawnTimers.delete(id);
+      }
+
       // Clear persisted respawn config
       this.screenManager.clearRespawnConfig(id);