fix(tts): align MiniMax TTS defaults with current API and add GroupId support

Follow-up on @pty819's t2a_v2 endpoint fix:

- Default model: speech-02 -> speech-02-hd (bare 'speech-02' is not in the
  supported enum; t2a_v2 rejects it with 400). Official enum: speech-01-hd,
  speech-01-turbo, speech-02-hd, speech-02-turbo, speech-2.6-hd/turbo,
  speech-2.8-hd/turbo.
- Default voice: female-shaonv -> English_expressive_narrator. The
  legacy speech-01-series short ID doesn't resolve cleanly on the
  speech-02+ models that are now the default.
- Default base URL: api.minimaxi.com -> api.minimax.io (matches the
  canonical host in the published docs; api-uw.minimax.io is the
  reduced-latency alt).
- Add GroupId support via tts.minimax.group_id config or MINIMAX_GROUP_ID
  env var. Some MiniMax accounts scope TTS requests by group; without it,
  requests 401. Only appended when not already in the user's base_url.

Tests rewritten to cover both the default t2a_v2 path (hex-encoded audio
in JSON, nested voice_setting/audio_setting) and the legacy
text_to_speech path (raw audio bytes, flat payload). Adds coverage for
GroupId config/env wiring and error surfacing.

Also adds AUTHOR_MAP entry for pty819's GitHub-noreply email.

tools/tts_tool.py

@@ -159,9 +159,9 @@ DEFAULT_KITTENTTS_VOICE = "Jasper"
 DEFAULT_PIPER_VOICE = "en_US-lessac-medium"  # balanced size/quality
 DEFAULT_OPENAI_VOICE = "alloy"
 DEFAULT_OPENAI_BASE_URL = "https://api.openai.com/v1"
-DEFAULT_MINIMAX_MODEL = "speech-02"
-DEFAULT_MINIMAX_VOICE_ID = "female-shaonv"
-DEFAULT_MINIMAX_BASE_URL = "https://api.minimaxi.com/v1/t2a_v2"
+DEFAULT_MINIMAX_MODEL = "speech-02-hd"
+DEFAULT_MINIMAX_VOICE_ID = "English_expressive_narrator"
+DEFAULT_MINIMAX_BASE_URL = "https://api.minimax.io/v1/t2a_v2"
 DEFAULT_MISTRAL_TTS_MODEL = "voxtral-mini-tts-2603"
 DEFAULT_MISTRAL_TTS_VOICE_ID = "c69964a6-ab8b-4f8a-9465-ec0925096ec8"  # Paul - Neutral
 DEFAULT_XAI_VOICE_ID = "eve"
@@ -991,6 +991,18 @@ def _generate_minimax_tts(text: str, output_path: str, tts_config: Dict[str, Any
     sample_rate = mm_config.get("sample_rate", 32000)
     bitrate = mm_config.get("bitrate", 128000)
 
+    # MiniMax accounts scope TTS requests by GroupId.  When present, the docs
+    # show it as a ?GroupId=<id> query param on the t2a_v2 URL.  Accept it
+    # from config or from the MINIMAX_GROUP_ID env var; only attach when the
+    # URL doesn't already carry one.
+    group_id = (
+        str(mm_config.get("group_id") or "").strip()
+        or (get_env_value("MINIMAX_GROUP_ID") or "").strip()
+    )
+    if group_id and "GroupId=" not in base_url:
+        sep = "&" if "?" in base_url else "?"
+        base_url = f"{base_url}{sep}GroupId={group_id}"
+
     headers = {
         "Content-Type": "application/json",
         "Authorization": f"Bearer {api_key}",