feat: CDP 接管开关 + 扫码登录面板 + Docker 部署

- runner: enable_cdp_mode 从硬编码 False 改为系统设置 cdp_enabled。服务器部署下爬虫接管已开启远程调试的 Chrome（默认 9222），复用其 profile 登录态；本机桌面默认仍为关，行为不变
- qrlogin: 新增 CDP 扫码登录。Chrome 在服务器上跑于 Xvfb，show_qrcode 依赖的 PIL 桌面看图程序不存在，二维码无处可显示；改为经 CDP 从页面取出二维码交给 WebUI 渲染。刻意复用 browser.contexts[0]（新建 context 是无痕 profile，扫了也白扫），且绝不调用 browser.close()（会连带关掉操作者自己的 Chrome）
- webui: 设置页新增扫码面板，替换原本跳到采集页看终端二维码的入口
- Dockerfile / .dockerignore / docker-compose.yml: 服务器部署。host 网络是必需而非图省事——容器里 127.0.0.1:9222 必须落到宿主机回环
- UPSTREAM.md: 补充 gitcode 镜像，用于 GitHub 大包传输必断时补历史

webui/src/hooks/useMonitor.ts

@@ -204,6 +204,46 @@ export function useClearCookie() {
   })
 }
 
+// --- QR login (over CDP) ---------------------------------------------------
+
+/** Polls only while a code is on screen; an idle session has nothing to watch. */
+export function useQrLoginStatus(polling: boolean) {
+  return useQuery({
+    queryKey: ['monitorQrLogin'],
+    queryFn: async () => (await monitorApi.getQrLogin()).data,
+    refetchInterval: polling ? 2000 : false,
+  })
+}
+
+export function useStartQrLogin() {
+  const queryClient = useQueryClient()
+  const platform = usePlatformParam()
+  return useMutation({
+    mutationFn: () => monitorApi.startQrLogin(platform),
+    onSuccess: (response) => {
+      queryClient.setQueryData(['monitorQrLogin'], response.data)
+    },
+    onError: (error: Error) => {
+      // The backend's reason -- "Chrome is not reachable on ...", "no QR on the
+      // page" -- is the entire value here, and axios would flatten it to
+      // "Request failed with status code 502".
+      const detail = (error as { response?: { data?: { detail?: string } } })?.response
+        ?.data?.detail
+      toast.error(`获取二维码失败：${detail ?? error.message}`)
+    },
+  })
+}
+
+export function useCancelQrLogin() {
+  const queryClient = useQueryClient()
+  return useMutation({
+    mutationFn: () => monitorApi.cancelQrLogin(),
+    onSuccess: (response) => {
+      queryClient.setQueryData(['monitorQrLogin'], response.data)
+    },
+  })
+}
+
 // --- Settings -------------------------------------------------------------
 
 export function useSettings() {