feat(tts): complete KittenTTS integration (tools/setup/docs/tests)

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

hermes_cli/tools_config.py

@@ -182,6 +182,14 @@ TOOL_CATEGORIES = {
                 ],
                 "tts_provider": "gemini",
             },
+            {
+                "name": "KittenTTS",
+                "badge": "local · free",
+                "tag": "Lightweight local ONNX TTS (~25MB), no API key",
+                "env_vars": [],
+                "tts_provider": "kittentts",
+                "post_setup": "kittentts",
+            },
         ],
     },
     "web": {
@@ -423,6 +431,36 @@ def _run_post_setup(post_setup_key: str):
             _print_warning("    Node.js not found. Install Camofox via Docker:")
             _print_info("      docker run -p 9377:9377 -e CAMOFOX_PORT=9377 jo-inc/camofox-browser")
 
+    elif post_setup_key == "kittentts":
+        try:
+            __import__("kittentts")
+            _print_success("    kittentts is already installed")
+            return
+        except ImportError:
+            pass
+        import subprocess
+        _print_info("    Installing kittentts (~25-80MB model, CPU-only)...")
+        wheel_url = (
+            "https://github.com/KittenML/KittenTTS/releases/download/"
+            "0.8.1/kittentts-0.8.1-py3-none-any.whl"
+        )
+        try:
+            result = subprocess.run(
+                [sys.executable, "-m", "pip", "install", "-U", wheel_url, "soundfile", "--quiet"],
+                capture_output=True, text=True, timeout=300,
+            )
+            if result.returncode == 0:
+                _print_success("    kittentts installed")
+                _print_info("    Voices: Jasper, Bella, Luna, Bruno, Rosie, Hugo, Kiki, Leo")
+                _print_info("    Models: KittenML/kitten-tts-nano-0.8-int8 (25MB), micro (41MB), mini (80MB)")
+            else:
+                _print_warning("    kittentts install failed:")
+                _print_info(f"      {result.stderr.strip()[:300]}")
+                _print_info(f"    Run manually: python -m pip install -U '{wheel_url}' soundfile")
+        except subprocess.TimeoutExpired:
+            _print_warning("    kittentts install timed out (>5min)")
+            _print_info(f"    Run manually: python -m pip install -U '{wheel_url}' soundfile")
+
     elif post_setup_key == "rl_training":
         try:
             __import__("tinker_atropos")