feat(chat): implement external browser prompt logic and update tests

src/app/chat/components/browser-hint-overlay.tsx

@@ -14,7 +14,6 @@ import { useEffect, useState } from "react";
 import { ExternalLink } from "lucide-react";
 
 import { openChatInExternalBrowser } from "@/lib/chat/chat_external_browser";
-import { BrowserDetector } from "@/utils";
 
 import styles from "./browser-hint-overlay.module.css";
 
@@ -39,13 +38,11 @@ export function BrowserHintOverlay({
   forceShow = false,
   autoCollapseDelayMs = DEFAULT_AUTO_COLLAPSE_DELAY_MS,
 }: BrowserHintOverlayProps) {
-  // lazy initializer：首次渲染即计算（避免 useEffect 中调 setState 的 lint 错）
-  const [isInAppBrowser] = useState(BrowserDetector.isInAppBrowser);
   const [isExpanded, setIsExpanded] = useState(true);
   const [hasAutoCollapsed, setHasAutoCollapsed] = useState(false);
 
-  // 开发模式或应用内浏览器才显示
-  const shouldShow = forceShow || isInAppBrowser;
+  // 展示条件由调用方控制；forceShow 保留给开发/测试入口。
+  const shouldShow = forceShow;
 
   useEffect(() => {
     if (!shouldShow || hasAutoCollapsed || autoCollapseDelayMs <= 0) return;