feat(ui): searchable combobox across data-driven dropdowns
- new ui/combobox primitive (popover plus cmdk): search input, scrolling
list, trigger-width popover, per-option disabled and hint lines
- converts every data-driven single-value select site-wide (blueprints,
factions, accounts, assignments, NPCs, structures, locker items, seats,
missions, ranks, resources, mod lists, event targets, sprints)
- long multi-select checkbox menus (event log types, kanban labels) gain
search inputs following the resource picker pattern
- static short enum selects stay as plain selects