[tmm]

The web app's creator, assignee, and label pickers are comboboxes you can type into. zbugs-gpui showed plain scrolling menus. Now those five pickers (the Creator, Assignee, and Labels filters, and the issue's assignee and labels) open a popover with:

• a focused search field, ranked by a port of zbugs' fuzzySearch (the start of a name counts most, then runs of characters; ties sort by name), with a unit test;
• avatars beside users, as the web user picker shows;
• ↑/↓ to move one highlight, which the pointer also moves, and Enter or a click to pick;
• the label pickers staying open so you can toggle several labels, while a user pick or a clearing entry ("Anyone", "Any label") closes it;
• Escape or a click outside to close.

The short pickers (project, notifications, visibility) keep their menus. The new code is src/picker.rs, inside the app. Choice moved there and gained an avatar.

Checked on macOS: typing ar in Creator ranks arv first, then cesara, darkgnotic, ingar, and jamischarles. Down then Enter filters to cesara. Typing pe in an issue's Labels and pressing Enter adds papercut and leaves the picker open. Clippy is clean with and without e2e, cargo test passes, and the end-to-end run passes online and offline.