Two changes that pair with each other:
1. connect_auto_with_fresh_tab now does a Runtime.evaluate "1"
round-trip after creating the fresh tab. This catches the zombie
CDP socket case (process alive, websocket dead) where every step
up to that point reports success but the next user command would
silently no-op against a dead session. Failing here lets the
caller surface a proper "CDP session unresponsive" error instead
of returning Ok and letting `agent-browser open URL` exit 0 with
a still-blank tab.
2. handle_wait now recognizes @ref selectors (e.g. `wait @e8 --gone`).
It polls resolve_element_object_id, which already runs the
verify_ref_identity check from 007fd1b — so:
- `wait @e8` succeeds while the original element is
still mounted with its snapshot role+name
- `wait @e8 --gone` succeeds when the ref's identity changes
(modal closed, button re-textified, etc.)
This gives users the "assert modal still open" primitive that
prior versions could only approximate with screenshots.