feat: add NeuTTS optional skill + local TTS provider backend

* feat(skills): add bundled neutts optional skill

Add NeuTTS optional skill with CLI scaffold, bootstrap helper, and
sample voice profile. Also fixes skills_hub.py to handle binary
assets (WAV files) during skill installation.

Changes:
- optional-skills/mlops/models/neutts/ — skill + CLI scaffold
- tools/skills_hub.py — binary asset support (read_bytes, write_bytes)
- tests/tools/test_skills_hub.py — regression tests for binary assets

* feat(tts): add NeuTTS as local TTS provider backend

Add NeuTTS as a fourth TTS provider option alongside Edge, ElevenLabs,
and OpenAI. NeuTTS runs fully on-device via neutts_cli — no API key
needed.

Provider behavior:
- Explicit: set tts.provider to 'neutts' in config.yaml
- Fallback: when Edge TTS is unavailable and neutts_cli is installed,
  automatically falls back to NeuTTS instead of failing
- check_tts_requirements() now includes NeuTTS in availability checks

NeuTTS outputs WAV natively. For Telegram voice bubbles, ffmpeg
converts to Opus (same pattern as Edge TTS).

Changes:
- tools/tts_tool.py — _generate_neutts(), _check_neutts_available(),
  provider dispatch, fallback logic, Opus conversion
- hermes_cli/config.py — tts.neutts config defaults

---------

Co-authored-by: unmodeled-tyler <unmodeled.tyler@proton.me>

tests/tools/test_skills_hub.py

@@ -10,6 +10,7 @@ from tools.skills_hub import (
     LobeHubSource,
     SkillsShSource,
     WellKnownSkillSource,
+    OptionalSkillSource,
     SkillMeta,
     SkillBundle,
     HubLockFile,
@@ -20,6 +21,7 @@ from tools.skills_hub import (
     unified_search,
     append_audit_log,
     _skill_meta_to_dict,
+    quarantine_bundle,
 )
 
 
@@ -824,3 +826,68 @@ class TestSkillMetaToDict:
         restored = SkillMeta(**d)
         assert restored.name == meta.name
         assert restored.trust_level == meta.trust_level
+
+
+# ---------------------------------------------------------------------------
+# Official skills / binary assets
+# ---------------------------------------------------------------------------
+
+
+class TestOptionalSkillSourceBinaryAssets:
+    def test_fetch_preserves_binary_assets(self, tmp_path):
+        optional_root = tmp_path / "optional-skills"
+        skill_dir = optional_root / "mlops" / "models" / "neutts"
+        (skill_dir / "assets" / "neutts-cli" / "samples").mkdir(parents=True)
+        (skill_dir / "SKILL.md").write_text(
+            "---\nname: neutts\ndescription: test\n---\n\nBody\n",
+            encoding="utf-8",
+        )
+        wav_bytes = b"RIFF\x00\x01fakewav"
+        (skill_dir / "assets" / "neutts-cli" / "samples" / "jo.wav").write_bytes(
+            wav_bytes
+        )
+        (skill_dir / "assets" / "neutts-cli" / "samples" / "jo.txt").write_text(
+            "hello\n", encoding="utf-8"
+        )
+        pycache_dir = skill_dir / "assets" / "neutts-cli" / "src" / "neutts_cli" / "__pycache__"
+        pycache_dir.mkdir(parents=True)
+        (pycache_dir / "cli.cpython-312.pyc").write_bytes(b"junk")
+
+        src = OptionalSkillSource()
+        src._optional_dir = optional_root
+
+        bundle = src.fetch("official/mlops/models/neutts")
+
+        assert bundle is not None
+        assert bundle.files["assets/neutts-cli/samples/jo.wav"] == wav_bytes
+        assert bundle.files["assets/neutts-cli/samples/jo.txt"] == b"hello\n"
+        assert "assets/neutts-cli/src/neutts_cli/__pycache__/cli.cpython-312.pyc" not in bundle.files
+
+
+class TestQuarantineBundleBinaryAssets:
+    def test_quarantine_bundle_writes_binary_files(self, tmp_path):
+        import tools.skills_hub as hub
+
+        hub_dir = tmp_path / "skills" / ".hub"
+        with patch.object(hub, "SKILLS_DIR", tmp_path / "skills"), \
+             patch.object(hub, "HUB_DIR", hub_dir), \
+             patch.object(hub, "LOCK_FILE", hub_dir / "lock.json"), \
+             patch.object(hub, "QUARANTINE_DIR", hub_dir / "quarantine"), \
+             patch.object(hub, "AUDIT_LOG", hub_dir / "audit.log"), \
+             patch.object(hub, "TAPS_FILE", hub_dir / "taps.json"), \
+             patch.object(hub, "INDEX_CACHE_DIR", hub_dir / "index-cache"):
+            bundle = SkillBundle(
+                name="neutts",
+                files={
+                    "SKILL.md": "---\nname: neutts\n---\n",
+                    "assets/neutts-cli/samples/jo.wav": b"RIFF\x00\x01fakewav",
+                },
+                source="official",
+                identifier="official/mlops/models/neutts",
+                trust_level="builtin",
+            )
+
+            q_path = quarantine_bundle(bundle)
+
+        assert (q_path / "SKILL.md").read_text(encoding="utf-8").startswith("---")
+        assert (q_path / "assets" / "neutts-cli" / "samples" / "jo.wav").read_bytes() == b"RIFF\x00\x01fakewav"