fix(stealth): 修复 headed 模式下 stealth 失效并统一策略

- 修复 launch 协议未透传 stealth 导致 --headed 下补丁失效的问题\n- 在 BrowserManager 引入 StealthPolicy，统一 local/CDP/provider 能力决策\n- 增加 launch 返回 stealth 状态并在 --debug 输出连接类型与能力\n- 补充 local/CDP 回归测试与 bot.sannysoft.com 自动检查脚本\n- 同步 README、CLI help、技能文档与 CDP 文档中的 stealth 能力矩阵

docs/src/app/cdp-mode/page.mdx

@@ -75,6 +75,23 @@ Or set it globally via config or environment variable:
 AGENT_BROWSER_COLOR_SCHEME=dark agent-browser --cdp 9222 open https://example.com
 ```
 
+## Stealth behavior
+
+`--stealth` is enabled by default across connection modes, but capabilities depend on how you connect:
+
+<table>
+  <thead>
+    <tr><th>Connection type</th><th>Stealth capabilities</th></tr>
+  </thead>
+  <tbody>
+    <tr><td>Local launch</td><td>Chromium launch args + context init scripts</td></tr>
+    <tr><td>CDP / auto-connect</td><td>Context init scripts</td></tr>
+    <tr><td>Cloud providers</td><td>Context init scripts (Kernel may also apply provider-managed stealth)</td></tr>
+  </tbody>
+</table>
+
+Use `--debug` to print the active connection type and applied stealth capabilities.
+
 ## Use cases
 
 This enables control of: