feat: settings web UI (models / STT / TTS speed / language / LLM instructions)

Adds /settings (served by the bridge) to change the LLM model (from installed
Ollama models), Whisper model, TTS engine + MeloTTS speed, output language,
agentic max-turns, thinking mode, and free-form LLM instructions — live, with a
'apply' that restarts the bridge + TTS worker. Settings persist to the runtime
config JSON; engine reads output_language + llm_instructions and the TTS worker
reads melo_speed from it. Bridge port publishable for access.

.env.example

@@ -187,3 +187,10 @@ COMPOSE_FILE=docker-compose.yml:docker-compose.gpu-linux.yml
 # OLLAMA_CHAT_MODEL=qwen2.5:3b   # speed (fits easily, faster on 8GB GPUs)
 # WHISPER_MODEL=small            # small frees VRAM for a bigger LLM; medium=more accurate
 # MELO_DEVICE=cuda               # cpu if no GPU on the bot host
+
+# --- Settings web UI (http://localhost:8765/settings on the bot host) ---
+# To reach it, expose the bridge to the host loopback:
+#   BRIDGE_HOST=0.0.0.0
+#   SETTINGS_PUBLISH_BIND=127.0.0.1   # 0.0.0.0 to allow LAN access (no auth)
+# Change models / STT / TTS speed / language / LLM instructions live; "적용"
+# restarts the bridge + TTS worker so changes take effect.