feat(connect): native-messaging transport — zero-token connect to real Chrome

Optimal architecture (chosen over the WS+token copy): the ab-connect extension
talks to a local agent-browser native-messaging host. No localhost port, no
token — Chrome authenticates the extension to the host by id. This is the
codex/claude-style "install once, no per-use confirmation" model.

- extensions/ab-connect: rewritten transport WebSocket+token → native messaging
  (chrome.runtime.connectNative). Pinned the extension id via a manifest `key`
  (→ bdoiejojpjogcjojeladhioioijhgade) so the host manifest can authorize it.
  Kept the proven chrome.debugger attach + Target.attachedToTarget emulation;
  dropped WS/token/options. Rebranded to "agent-browser connect".
- cli connect.rs: `agent-browser extension install` writes the native-messaging
  host manifest (Chrome/Chromium/Edge/Brave) + a launcher; hidden `__nm-host`
  speaks the 4-byte-length native-messaging framing.

Validated end-to-end on real Chrome: Chrome spawned the host (origin matched the
pinned id) and the extension attached the user's real logged-in tabs, streaming
Target.attachedToTarget over native messaging — zero token, zero port.

Next: bridge the host to the daemon relay (relay.rs) + CdpClient so
`agent-browser click/eval/...` drives those tabs.

extensions/ab-connect/NOTICE.md

@@ -1,10 +1,11 @@
 # Attribution
 
-The `ab-connect` extension is adapted from **openclaw-browser-relay**
-by chengyixu — https://github.com/chengyixu/openclaw-browser-relay
-(MIT License, per its README).
+The chrome.debugger attach + CDP Target handling in `background.js` is adapted
+from **openclaw-browser-relay** by chengyixu
+(https://github.com/chengyixu/openclaw-browser-relay, MIT per its README).
 
-Changes for agent-browser-stealth: rebranded; points at the agent-browser
-daemon's local relay endpoint instead of the OpenClaw gateway; protocol
-otherwise preserved (connect handshake, forwardCDPCommand/forwardCDPEvent,
-ping/pong).
+Changes for agent-browser-stealth: rebranded to "agent-browser connect"; the
+transport is rewritten from a localhost WebSocket + shared token to Chrome
+**native messaging** (host `com.agent_browser.connect`) — no port, no token,
+Chrome authenticates the extension to the host by id. WebSocket/token/options
+code removed.