feat(cleanup): default idle-shutdown + keep — stop leaving scratch tabs/groups behind

Agents finish a task and just stop (never calling `close`), so daemons used to
run forever, leaving their per-session scratch tabs + tab group in the user's
Chrome. Two cases now handled:

- Default idle timeout (10 min; AGENT_BROWSER_IDLE_TIMEOUT_MS overrides, 0
  disables). On idle the daemon close()s the tabs IT created → the empty tab
  group is auto-removed by Chrome. Timer resets on every command, so active
  sessions are untouched. Adopted user tabs are never owned, so never closed.
- `keep` — leave the ACTIVE tab for the user: unown it (exempt from
  close/idle) + ask the extension to ungroup it (ABExt.ungroupTab → 0.4.12) so
  it becomes a normal tab. Scratch gets cleaned, deliverable tabs stay.

Also fix two clippy violations in the concurrently-landed #47 viewport code
(manual char comparison + iter().any→contains) that were failing main's CI.

ext 0.4.12: handle ABExt.ungroupTab (chrome.tabs.ungroup). 870 tests pass.

extensions/ab-connect/background.js

@@ -288,6 +288,19 @@ async function handleForwardCdpCommand(msg) {
   const params = msg?.params?.params || undefined
   const sessionId = typeof msg?.params?.sessionId === 'string' ? msg.params.sessionId : undefined
 
+  // Non-CDP extension commands (ABExt.*) the daemon sends. `ungroupTab` removes a
+  // tab from its per-session tab group so a `keep`-marked tab is left for the user
+  // as a normal, ungrouped tab (the group can then be cleaned up). Best-effort.
+  if (method === 'ABExt.ungroupTab') {
+    const tabId = tabIdFromSession(sessionId) ?? tabForSession(sessionId)
+    if (tabId != null && chrome.tabs.ungroup) {
+      try {
+        await chrome.tabs.ungroup(tabId)
+      } catch {}
+    }
+    return { ungrouped: tabId ?? null }
+  }
+
   // Browser-level Target methods that map onto chrome.tabs.
   if (method === 'Target.createTarget') {
     const url = typeof params?.url === 'string' && params.url ? params.url : 'about:blank'

extensions/ab-connect/manifest.json

@@ -1,8 +1,8 @@
 {
   "manifest_version": 3,
   "name": "chrome-use",
-  "version": "0.4.11",
-  "description": "Let chrome-use drive your logged-in Chrome \u2014 install once, no token, no per-use confirmation.",
+  "version": "0.4.12",
+  "description": "Let chrome-use drive your logged-in Chrome — 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",