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.

scripts/release.py

@@ -223,6 +223,7 @@ AUTHOR_MAP = {
     "hitesh@gmail.com": "htsh",
     "pty819@outlook.com": "pty819",
     "pty819@users.noreply.github.com": "pty819",
+    "14341805+pty819@users.noreply.github.com": "pty819",
     "517024110@qq.com": "chennest",
     # Curator fixes (Apr 30 2026)
     "yuxiangl490@gmail.com": "y0shua1ee",