bug: agent-browser select fails on custom ARIA combobox widgets

[juniper929]

Problem

agent-browser select on custom ARIA combobox widgets (Radix UI, Headless UI, etc.)
fails with
Element not found, while native <select> elements work correctly.

Steps to Reproduce

Custom ARIA combobox — fails:

agent-browser open "https://ybqcgqwz8b.coze.site"
agent-browser snapshot
# → combobox "Position *" [ref=e3]: Select Position

agent-browser select e3 "Product Manager"
# → ✗ Element "e3" not found or not visible.

Native <select> — works:

agent-browser open "https://w7nzypr53r.coze.site"
agent-browser snapshot
# → combobox "Target Position" [ref=e2]
#     - option "Frontend Developer" [ref=e4]
#     - option "Backend Developer" [ref=e5]
#     ...

agent-browser select e2 "Backend Developer"
# → ✓ Done

Root Cause

Chrome's accessibility tree reports role="combobox" for both native
<select> elements
and custom ARIA widgets. The existing select implementation only handles
native <select>,
which exposes its options directly in the AX tree. Custom combobox widgets
(Radix UI, etc.)
render options dynamically — only after the trigger is clicked — so
Element not found is
returned before the dropdown is ever opened.

Expected Behavior

agent-browser select should support custom ARIA combobox widgets（widely used in modern frontend frameworks） the same way it
supports native elements — selecting the specified option by text. Labels: bug