feat: 浏览器扩展支持交互式页面操作 (browser_act)

在原有只读抓取 (browser_fetch_page) 基础上，新增 observe→act 循环，
让 Agent 能在用户的 Chrome 中实际操作网页：点击/输入/滚动/等待/页内跳转。

后端：
- 新工具 browser_act，按 session 复用标签页，返回带编号的可交互元素清单+正文
- browser_context 任务队列扩展 kind/session_id/action 与 observation 结果
- /api/browser-context 路由下发 act 任务、接收 observation
- BrowserContextConfig 增加 actions_enabled 等开关，tools.py 两级门控
- 接线 app.py 路由挂载、app_config.py 配置字段、config.yaml 工具注册

前端：
- ChatPage 处理「发送当前页」回跳的 browser_context query 参数并自动提交

扩展 (browser-extension/deer-web-clipper)：
- shared.js 自包含注入函数 deerObservePage / deerPerformAction
- background.js 按 kind 分发任务，session→tab 映射存 chrome.storage.session

测试：tests/test_browser_act.py（队列往返 + 工具校验 + 模拟扩展成功路径，8 passed）

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend-web/src/pages/ChatPage.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useRouter } from "next/navigation";
+import { useRouter, useSearchParams } from "next/navigation";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { toast } from "sonner";
 
@@ -41,9 +41,47 @@ import { textOfMessage } from "@/core/threads/utils";
 import { env } from "@/env";
 import { cn } from "@/lib/utils";
 
+const BROWSER_CONTEXT_PARAM_KEYS = [
+  "browser_context",
+  "bc_filename",
+  "bc_size",
+  "bc_path",
+  "bc_prompt",
+] as const;
+
+function clearBrowserContextParamsFromHash() {
+  if (typeof window === "undefined") return;
+  const hash = window.location.hash;
+  if (!hash.startsWith("#")) return;
+  const hashBody = hash.slice(1);
+  const queryStart = hashBody.indexOf("?");
+  if (queryStart < 0) return;
+
+  const path = hashBody.slice(0, queryStart);
+  const search = hashBody.slice(queryStart + 1);
+  const params = new URLSearchParams(search);
+  let changed = false;
+  for (const key of BROWSER_CONTEXT_PARAM_KEYS) {
+    if (params.has(key)) {
+      params.delete(key);
+      changed = true;
+    }
+  }
+  if (!changed) return;
+
+  const nextSearch = params.toString();
+  const nextHash = nextSearch ? `#${path}?${nextSearch}` : `#${path}`;
+  window.history.replaceState(
+    null,
+    "",
+    `${window.location.pathname}${window.location.search}${nextHash}`,
+  );
+}
+
 export default function ChatPage() {
   const routeBase = useRouteBase();
   const router = useRouter();
+  const searchParams = useSearchParams();
   const { t } = useI18n();
   const [showFollowups, setShowFollowups] = useState(false);
   const [hasStartedConversation, setHasStartedConversation] = useState(false);
@@ -62,6 +100,7 @@ export default function ChatPage() {
   const [selectedAgentId, setSelectedAgentId] = useState<string | null>(null);
   const [agentHandoffPending, setAgentHandoffPending] = useState(false);
   const agentHandoffPendingRef = useRef(false);
+  const browserContextAutoSubmitRef = useRef<string | null>(null);
   const { agents: selectorAgents, isLoading: selectorLoading } =
     useAgentSelector();
   const { selectedArtifact } = useArtifacts();
@@ -242,6 +281,75 @@ export default function ChatPage() {
     [sendMessage, threadId],
   );
 
+  useEffect(() => {
+    const token = searchParams.get("browser_context")?.trim();
+    if (!token || browserContextAutoSubmitRef.current === token) {
+      return;
+    }
+    if (!threadId || isNewThread || thread.isLoading || agentHandoffPending) {
+      return;
+    }
+
+    const consumedKey = `deerflow.browser-context.consumed.${token}`;
+    if (window.sessionStorage.getItem(consumedKey)) {
+      browserContextAutoSubmitRef.current = token;
+      clearBrowserContextParamsFromHash();
+      return;
+    }
+
+    const filename = searchParams.get("bc_filename")?.trim();
+    const path = searchParams.get("bc_path")?.trim();
+    const size = Number(searchParams.get("bc_size") ?? "0");
+    const prompt =
+      searchParams.get("bc_prompt")?.trim() ||
+      "请基于刚刚发送的网页内容，先用中文总结要点，并等待我继续提问。";
+
+    if (!filename || !path || !Number.isFinite(size) || size < 0) {
+      browserContextAutoSubmitRef.current = token;
+      clearBrowserContextParamsFromHash();
+      toast.error("网页上下文参数不完整，无法自动发送到 Deer");
+      return;
+    }
+
+    browserContextAutoSubmitRef.current = token;
+    window.sessionStorage.setItem(consumedKey, "1");
+    clearBrowserContextParamsFromHash();
+    setHasStartedConversation(true);
+
+    void sendMessage(
+      threadId,
+      { text: prompt, files: [] },
+      undefined,
+      {
+        additionalKwargs: {
+          browser_context: {
+            source: "chrome-extension",
+            token,
+          },
+          files: [
+            {
+              filename,
+              size,
+              path,
+              status: "uploaded",
+            },
+          ],
+        },
+      },
+    ).catch((err) => {
+      toast.error(
+        err instanceof Error ? err.message : "网页上下文发送失败，请重试",
+      );
+    });
+  }, [
+    searchParams,
+    threadId,
+    isNewThread,
+    thread.isLoading,
+    agentHandoffPending,
+    sendMessage,
+  ]);
+
   // Persist the picked agent the moment it changes so the next new chat
   // defaults to it — even if the user never sends a message this session.
   // Passing null (the ✕ clear) wipes the stored preference.