fix: Chatterbox uses separate classes per variant, remove turbo

ChatterboxTTS and ChatterboxMultilingualTTS are separate classes.
Turbo variant doesn't exist in chatterbox-tts 0.1.7.
Multilingual generate() requires language_id parameter.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

kischdle/llmux/tests/test_routes.py

@@ -45,7 +45,7 @@ def test_list_models_returns_16(client, auth_headers):
     assert resp.status_code == 200
     body = resp.json()
     assert body["object"] == "list"
-    assert len(body["data"]) == 16
+    assert len(body["data"]) == 15
 
 
 def test_list_models_contains_expected_names(client, auth_headers):