Fix voice join against LiveKit 0.13+ and tidy up command messages

revoice.js reads `room.isConnected()`, but @livekit/rtc-node turned that
into a getter, so every join threw "this.room.isConnected is not a
function" before the bot ever reached the channel. The player no longer
touches that getter: readiness comes from the connection's own join /
roomfetched events and is cleared when it reports the offline state.

Also delete the invoking chat message once a command is recognised
(DELETE_COMMAND_MESSAGES, on by default) so channels stay readable;
failures are non-fatal since it needs ManageMessages.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/bot/index.ts

@@ -66,6 +66,13 @@ async function handleMessage(manager: MusicManager, message: Message): Promise<v
   const command = findCommand(rawName);
   if (!command) return;
 
+  if (config.DELETE_COMMAND_MESSAGES) {
+    // Fire-and-forget: a missing ManageMessages permission must not block playback.
+    void message.delete().catch((err) => {
+      log.debug({ err, command: command.name }, "could not delete command message");
+    });
+  }
+
   const ctx: CommandContext = {
     manager,
     serverId,