fix(tools): add raise_for_status for MiniMax t2a_v2 TTS path

The MiniMax t2a_v2 code path calls response.json() without first
checking the HTTP status code. If the API returns HTTP 4xx/5xx with
non-JSON content (e.g. HTML error page), response.json() raises an
opaque JSONDecodeError instead of a clear HTTPError.

The non-t2a_v2 path already has response.raise_for_status() at line
1299. Add the same check before response.json() in the t2a_v2 path
for consistent error handling.

tools/tts_tool.py

@@ -1261,6 +1261,7 @@ def _generate_minimax_tts(text: str, output_path: str, tts_config: Dict[str, Any
 
     if is_t2a_v2:
         # t2a_v2 returns JSON with hex-encoded audio
+        response.raise_for_status()
         result = response.json()
         base_resp = result.get("base_resp", {})
         status_code = base_resp.get("status_code", -1)