feat: add extra Mumble bot instances and TTS greeting

Support [[mumble.extra]] config for additional Mumble identities that
inherit connection settings from the main [mumble] section. Extra bots
get their own state DB and do not run the voice trigger by default.

Add TTS greeting on first connect via mumble.greet config option.
Merlin joins as a second identity with his own client certificate.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/voice.py

@@ -321,10 +321,22 @@ async def cmd_say(bot, message):
 
 
 async def on_connected(bot) -> None:
-    """Re-register listener after reconnect if listen or trigger is active."""
+    """Re-register listener after reconnect; play TTS greeting on first join."""
     if not _is_mumble(bot):
         return
     ps = _ps(bot)
+
+    # TTS greeting on first connect
+    greet = bot.config.get("mumble", {}).get("greet")
+    if greet and not ps.get("_greeted"):
+        ps["_greeted"] = True
+        # Wait for audio subsystem to be ready
+        for _ in range(20):
+            if bot._is_audio_ready():
+                break
+            await asyncio.sleep(0.5)
+        bot._spawn(_tts_play(bot, greet), name="voice-greet")
+
     if ps["listen"] or ps["trigger"]:
         _ensure_listener(bot)
         _ensure_flush_task(bot)