Feat: Frontend-Overhaul E — Lane-Editor, Routing-Policy (hot-reload) & Latenz-Karte

Teil 1: VoiceLatencyCard auf dem Dashboard (GET /api/voice/metrics, C2) —
zeigt STT/Vision/Chat-TTFB/TTS mit p50/p95/last + count.

Teil 2: UI-editierbare Routing-Policy. Neuer routing_policy.py (hot-reload JSON
unter MODELS_DIR/mc2-routing.json, Env=Defaults, atomarer Write, Validierung).
router_logic, gateway_proxy und gateway.routing_summary lesen jetzt live via
load_policy(); routing_summary ist lane-bewusst (chat/coding statt altem auto).
Neue Endpoints GET/PUT /api/routing/policy.

Teil 3: LaneEditor.tsx als ZONE im Cockpit (chat/coding-Aliase + Schwellen +
fast_no_think, Speichern/Default-je-Feld); Gateway-Node zeigt die Lanes.

Verifiziert: npm run build (tsc strict) clean, FastAPI TestClient (GET/PUT,
Validierung, Persistenz, Hot-reload durch die API), venv-Smoke (Routing).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/routers/gateway_proxy.py

@@ -4,7 +4,8 @@ from fastapi.responses import JSONResponse, StreamingResponse
 
 from config import LLAMA_SWAP_URL
 from services.gateway_stream import record_stream_chunk, record_usage
-from services.router_logic import FAST, FAST_NO_THINK, LANES, choose_for_lane
+from services.router_logic import LANES, choose_for_lane
+from services.routing_policy import load_policy
 
 router = APIRouter(prefix="/v1")
 
@@ -37,7 +38,8 @@ async def _proxy(path: str, request: Request):
         alias = requested
         routed = {"x-mc-routed-to": requested}
     # fast-Spur: Thinking aus für flotte Antworten (sofern Client es nicht selbst setzt).
-    if FAST_NO_THINK and alias == FAST and "chat_template_kwargs" not in body:
+    pol = load_policy()
+    if pol["fast_no_think"] and alias == pol["fast"] and "chat_template_kwargs" not in body:
         body["chat_template_kwargs"] = {"enable_thinking": False}
     url = f"{LLAMA_SWAP_URL}{path}"