Fix cosyvoice models not showing on model page and runtime import errors

- Model filter in ModelManagement was an allowlist missing cosyvoice prefix,
  replaced with inverse filter (everything except whisper = voice model)
- Shim training-only modules (cosyvoice.dataset.processor, matcha.utils.*)
  to prevent hyperpyyaml from importing pyarrow, pyworld, lightning etc.
- Patch torchaudio.load for 2.9+ compat (torchcodec now required by default)
- Add matplotlib to requirements (matcha hifigan imports it at module level)

app/src/components/ServerSettings/ModelManagement.tsx

@@ -394,14 +394,7 @@ export function ModelManagement() {
     setDetailOpen(true);
   };
 
-  const voiceModels =
-    modelStatus?.models.filter(
-      (m) =>
-        m.model_name.startsWith('qwen-tts') ||
-        m.model_name.startsWith('luxtts') ||
-        m.model_name.startsWith('chatterbox') ||
-        m.model_name.startsWith('tada'),
-    ) ?? [];
+  const voiceModels = modelStatus?.models.filter((m) => !m.model_name.startsWith('whisper')) ?? [];
   const whisperModels = modelStatus?.models.filter((m) => m.model_name.startsWith('whisper')) ?? [];
 
   // Build sections