Audit log: wider table, instant filters, searchable event dropdown

The Audit log now uses more of the screen — the table stretches to ~1300 px so long email addresses and event descriptions are no longer cramped. Filters apply as soon as you make a selection (no more Apply button): changing Who, Space, or When updates the feed immediately, and the event-type dropdown applies when you close it. The event dropdown also gained a search box that filters options by label, caps its height so it no longer overflows the screen, and can be dismissed by clicking outside it or pressing Escape.