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.

bridge/melo_worker.py

@@ -36,7 +36,26 @@ from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 HOST = os.environ.get("MELO_WORKER_HOST", "127.0.0.1")
 PORT = int(os.environ.get("MELO_WORKER_PORT", "8770"))
 LANGUAGE = os.environ.get("MELO_LANGUAGE", "KR")
-SPEED = float(os.environ.get("MELO_SPEED", "1.5"))
+
+
+def _resolve_speed() -> float:
+    """Speaking rate: the settings-UI value (runtime config JSON) wins, else the
+    MELO_SPEED env, else 1.5. Read at startup; the settings UI restarts this
+    worker on apply so a new value takes effect."""
+    try:
+        cp = os.environ.get("JARVIS_CONFIG_PATH", "/app/config/jarvis.json")
+        v = json.loads(open(cp, encoding="utf-8").read()).get("melo_speed")
+        if v is not None:
+            return float(v)
+    except Exception:
+        pass
+    try:
+        return float(os.environ.get("MELO_SPEED", "1.5"))
+    except ValueError:
+        return 1.5
+
+
+SPEED = _resolve_speed()
 DEVICE = os.environ.get("MELO_DEVICE", "cpu")
 
 # Model + speaker id are loaded once, guarded by a lock because MeloTTS