opentui(phase3): launcher integration — HERMES_TUI_ENGINE dual-engine

hermes --tui launches the native OpenTUI engine (Bun) when
HERMES_TUI_ENGINE=opentui (env) or display.tui_engine=opentui (config);
Ink stays the default and the shipping path is untouched.

- _resolve_tui_engine() (env > config > ink); refuses opentui on
  Windows/Termux (no Bun) -> falls back to ink with a notice.
- _make_opentui_argv() -> [bun, src/entry.real.tsx] (no build step).
- _bun_bin() with HERMES_BUN override.
- Branch at top of _make_tui_argv BEFORE _ensure_tui_node (Bun-only host
  must not bootstrap Node).
- Gate _launch_tui NODE_OPTIONS/--max-old-space-size on engine==ink (Bun
  is JSC; the V8 flag errors/ignores).

Verified end-to-end via tmux: real hermes --tui -> Bun -> OpenTUI ->
real Python gateway streamed a real reply. No-flag default still ink.

website/docs/user-guide/features/tts.md

@@ -66,10 +66,8 @@ tts:
     model: "voxtral-mini-tts-2603"
     voice_id: "c69964a6-ab8b-4f8a-9465-ec0925096ec8"  # Paul - Neutral (default)
   gemini:
-    model: "gemini-2.5-flash-preview-tts"  # or gemini-3.1-flash-tts-preview
+    model: "gemini-2.5-flash-preview-tts"  # or gemini-2.5-pro-preview-tts
     voice: "Kore"               # 30 prebuilt voices: Zephyr, Puck, Kore, Enceladus, Gacrux, etc.
-    audio_tags: false           # Enable hidden Gemini 3.1 TTS audio-tag insertion
-    persona_prompt_file: ""      # Optional Markdown/text file with Gemini voice direction
   xai:
     voice_id: "eve"             # or a custom voice ID — see docs below
     language: "en"              # ISO 639-1 code
@@ -99,34 +97,6 @@ tts:
 
 **Speed control**: The global `tts.speed` value applies to all providers by default. Each provider can override it with its own `speed` setting (e.g., `tts.openai.speed: 1.5`). Provider-specific speed takes precedence over the global value. Default is `1.0` (normal speed).
 
-### Gemini Persona Prompts
-
-Gemini TTS can follow natural-language performance direction. Set `tts.gemini.persona_prompt_file` to a local Markdown or text file that describes the voice persona. The file can include Gemini-style sections such as `AUDIO PROFILE`, `SCENE`, `DIRECTOR'S NOTES`, `SAMPLE CONTEXT`, and `TRANSCRIPT`.
-
-If the file contains `{transcript}` or `{{ transcript }}`, Hermes replaces that placeholder with the live TTS text. Otherwise, Hermes appends a labeled `TRANSCRIPT` section automatically. The persona prompt stays local and is not shown in the chat reply.
-
-```yaml
-tts:
-  provider: gemini
-  gemini:
-    voice: Algieba
-    persona_prompt_file: ~/.hermes/tts/butler-voice.md
-```
-
-### Gemini Audio Tags
-
-Gemini 3.1 Flash TTS supports freeform square-bracket audio tags such as `[whispers]`, `[excitedly]`, `[very slow]`, `[laughs]`, and other expressive delivery notes. Enable `tts.gemini.audio_tags` to have Hermes run a hidden rewrite pass before Gemini TTS. The rewrite inserts inline tags into the TTS script only; the visible chat reply stays unchanged.
-
-```yaml
-tts:
-  provider: gemini
-  gemini:
-    model: gemini-3.1-flash-tts-preview
-    audio_tags: true
-```
-
-The rewrite uses `auxiliary.tts_audio_tags` and defaults to your main chat model. Override that auxiliary task if you want tag insertion handled by a cheaper or faster model.
-
 
 ### Input length limits
 
@@ -139,7 +109,7 @@ Each provider has a documented per-request input-character cap. Hermes truncates
 | xAI | 15000 |
 | MiniMax | 10000 |
 | Mistral | 4000 |
-| Google Gemini | 32000 |
+| Google Gemini | 5000 |
 | ElevenLabs | Model-aware (see below) |
 | NeuTTS | 2000 |
 | KittenTTS | 2000 |