v2.22.0

Added

• STT segments + Whisper/Voxtral usage — Speech-to-text responses now carry
  timestamped segments and STT-specific usage on TranscriptionResponse. Two
  new common types are exported from esperanto.common_types:
  • TranscriptionSegment (text, start, end, optional
    metadata: Dict[str, Any]) — the per-item metadata escape hatch holds
    provider-specific extras such as avg_logprob, compression_ratio,
    no_speech_prob, confidence, and speaker, so the top-level interface
    stays uniform across providers.
  • TranscriptionUsage (input_seconds, input_tokens, output_tokens,
    total_tokens) — STT-aware usage with input_seconds for audio billing,
    distinct from the LLM Usage type.
    TranscriptionResponse gains a segments: Optional[List[TranscriptionSegment]]
    field (defaults to None). For Whisper-family providers (OpenAI, Groq,
    Azure), Esperanto now automatically requests response_format=verbose_json
    in the underlying HTTP call so callers receive segments and duration
    without any extra configuration ("Hot-Swap-First Defaults"). Mistral
    natively returns segments and a usage block with prompt_audio_seconds —
    both are now mapped onto the response. ElevenLabs and Google leave
    segments=None (they don't return them and Esperanto never synthesizes
    segments from text alone, per the "Unsupported Response Fields Stay None"
    principle). Resolves #146 (Whisper-family segments + usage) and #193
    (Azure parity). (#146, #193)

Changed

• TranscriptionResponse.usage is now Optional[TranscriptionUsage] (was
  Optional[Usage], the LLM token-usage type). No existing STT provider in
  Esperanto populated usage before this release, so callers reading from
  STT responses are not affected in practice. New STT-specific fields
  (input_seconds) are only available on the new type.