Builds on @AxDSan's PR #2109 to finish the KittenTTS wiring so the
provider behaves like every other TTS backend end to end.
- tools/tts_tool.py: `_check_kittentts_available()` helper and wire
into `check_tts_requirements()`; extend Opus-conversion list to
include kittentts (WAV → Opus for Telegram voice bubbles); point the
missing-package error at `hermes setup tts`.
- hermes_cli/tools_config.py: add KittenTTS entry to the "Text-to-Speech"
toolset picker, with a `kittentts` post_setup hook that auto-installs
the wheel + soundfile via pip.
- hermes_cli/setup.py: `_install_kittentts_deps()`, new choice + install
flow in `_setup_tts_provider()`, provider_labels entry, and status row
in the `hermes setup` summary.
- website/docs/user-guide/features/tts.md: add KittenTTS to the provider
table, config example, ffmpeg note, and the zero-config voice-bubble tip.
- tests/tools/test_tts_kittentts.py: 10 unit tests covering generation,
model caching, config passthrough, ffmpeg conversion, availability
detection, and the missing-package dispatcher branch.
E2E verified against the real `kittentts` wheel:
- WAV direct output (pcm_s16le, 24kHz mono)
- MP3 conversion via ffmpeg (from WAV)
- Telegram flow (provider in Opus-conversion list) produces
`codec_name=opus`, 48kHz mono, `voice_compatible=True`, and the
`[[audio_as_voice]]` marker
- check_tts_requirements() returns True when kittentts is installed
