feat(extension): add popup status page (paired/not-paired) for Web Store review

The biggest Web Store rejection risk for a CLI-bridge extension is "non-functional
without external software." Give ab-connect a visible standalone UI: a branded
popup that shows whether the native-messaging link to the local agent-browser CLI
is live (Connected + attached tab count, or Not paired with the install hint),
plus a one-line privacy statement (no tracking, no remote server) and a repo link.

- manifest: action.default_popup = popup.html; bump 0.4.0 -> 0.4.1
- background.js: track hostConnected; respond to {type:'ab-status'} from the popup
  and nudge a reconnect on open
- popup.html/popup.js: dark/cyan branded status page (MV3-CSP-safe: external JS,
  no inline handlers), with a safety timeout so it never hangs on "Checking…"
- repacked ab-connect.zip/.crx

extensions/ab-connect/manifest.json

@@ -1,8 +1,8 @@
 {
   "manifest_version": 3,
   "name": "agent-browser-stealth",
-  "version": "0.4.0",
-  "description": "Let agent-browser drive your logged-in Chrome — install once, no token, no per-use confirmation.",
+  "version": "0.4.1",
+  "description": "Let agent-browser drive your logged-in Chrome \u2014 install once, no token, no per-use confirmation.",
   "key": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA6vQIyscGIPYPZdSpPwPL0+0gxUROyRgCpmvCSDoc8XUm4qm97VbKnD9Ijc1lV22lNWZtE78gaRjt6BeSfuMgnBymnhLKjN1gU6AI5QUU0mrJyeHdWKvrKQR5FmsM2A7Xr1ykE2SiiS8zNUS3Y/6O5l+Nva7wrVy6E4a2dkBVQkOsu+DV+nEZvhIyuDY5D5SPXqNwUTWTaglwj5mjvHz36xSwCWlPmrtJ+ED0AUyrb2z4GIOmvk4kqtBVrh/UD058klLo4CkYOnIybB5aV6WYuwarfPY4bF/dLggPem+ewLNTUNBuwrxj/A4nUv0LJTuRO8rR7f8WR9qnRCY0Ic5saQIDAQAB",
   "icons": {
     "16": "icons/icon16.png",
@@ -24,6 +24,7 @@
     "type": "module"
   },
   "action": {
-    "default_title": "agent-browser-stealth"
+    "default_title": "agent-browser-stealth",
+    "default_popup": "popup.html"
   }
 }