feat: smart LAN detection for sidebar links via X-Forwarded-For and router probe

dashboard/backend/main.py

@@ -114,6 +114,23 @@ async def startup_event():
 async def health():
     return {"status": "ok"}
 
+@app.get("/api/client-ip")
+async def client_ip(request: Request):
+    ip = request.headers.get("x-forwarded-for", "").split(",")[0].strip() or request.client.host
+    lan = ip.startswith("192.168.31.") or (ip.startswith("100.") and _router_reachable())
+    return {"ip": ip, "lan": lan}
+
+def _router_reachable():
+    import socket
+    try:
+        s = socket.socket()
+        s.settimeout(1)
+        s.connect(("192.168.31.1", 80))
+        s.close()
+        return True
+    except Exception:
+        return False
+
 # Public auth endpoints
 app.include_router(auth.router, prefix="/api/auth", tags=["auth"])