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>

tests/test_voice.py

@@ -724,3 +724,75 @@ class TestTriggerMode:
         msg = _Msg(text="!listen")
         asyncio.run(_mod.cmd_listen(bot, msg))
         assert any("Trigger: claude" in r for r in bot.replied)
+
+
+# ---------------------------------------------------------------------------
+# TestGreeting
+# ---------------------------------------------------------------------------
+
+
+class TestGreeting:
+    def test_greet_on_first_connect(self):
+        """TTS greeting fires on first connect when configured."""
+        bot = _FakeBot()
+        bot.config = {"mumble": {"greet": "Hello there."}}
+        bot._is_audio_ready = lambda: True
+
+        spawned = []
+
+        def fake_spawn(coro, *, name=None):
+            spawned.append(name)
+            coro.close()
+            task = MagicMock()
+            task.done.return_value = False
+            return task
+
+        bot._spawn = fake_spawn
+        asyncio.run(_mod.on_connected(bot))
+        assert "voice-greet" in spawned
+
+    def test_greet_only_once(self):
+        """Greeting fires only on first connect, not on reconnect."""
+        bot = _FakeBot()
+        bot.config = {"mumble": {"greet": "Hello there."}}
+        bot._is_audio_ready = lambda: True
+
+        spawned = []
+
+        def fake_spawn(coro, *, name=None):
+            spawned.append(name)
+            coro.close()
+            task = MagicMock()
+            task.done.return_value = False
+            return task
+
+        bot._spawn = fake_spawn
+        asyncio.run(_mod.on_connected(bot))
+        assert spawned.count("voice-greet") == 1
+        asyncio.run(_mod.on_connected(bot))
+        assert spawned.count("voice-greet") == 1
+
+    def test_no_greet_without_config(self):
+        """No greeting when mumble.greet is not set."""
+        bot = _FakeBot()
+        bot.config = {}
+
+        spawned = []
+
+        def fake_spawn(coro, *, name=None):
+            spawned.append(name)
+            coro.close()
+            task = MagicMock()
+            task.done.return_value = False
+            return task
+
+        bot._spawn = fake_spawn
+        asyncio.run(_mod.on_connected(bot))
+        assert "voice-greet" not in spawned
+
+    def test_no_greet_non_mumble(self):
+        """Greeting skipped for non-Mumble bots."""
+        bot = _FakeBot(mumble=False)
+        bot.config = {"mumble": {"greet": "Hello there."}}
+        asyncio.run(_mod.on_connected(bot))
+        # Should not raise or try to greet