Rework column filters and toolbar toggles

- Remove the drag-and-drop FilterBuilder in favor of the existing
  '+ Add filter' row editor in the Column Filters popover
- Debounce filter value edits (400ms) so a query only fires after the
  user stops typing, fixing a race where the in-flight fetch guard
  silently dropped the final filter value
- Make every toolbar toggle (filter, sort, auto-refresh, show/hide
  columns, export, bulk actions) a clean plain toggle by wrapping the
  button + dropdown in a shared ref so the outside-click handler no
  longer fights the button click

AGENTS.md

@@ -290,7 +290,7 @@ Planned work is prioritized in the [Project Roadmap](./ROADMAP.md) (source of tr
 | Smart default sort | ✅ | 12-tier priority: updated_at → created_at → *_at → *_id → seq/rank/version |
 | Data grid pagination | ✅ | Page nav, page size selector persisted in settings |
 | Column filtering (server-side) | ✅ | eq, neq, contains, starts, ends, gt, lt, null, notnull pushed to SQL WHERE |
-| Visual filter builder | ✅ | Drag-and-drop column palette (@dnd-kit) with type-aware operators (textish → contains, else eq), AND semantics, persists in tab `filterRules` |
+| Visual filter builder | ✅ | Column Filters popover with a "+ Add filter" row editor (column / operator / value selects, per-rule remove, AND semantics, persists in tab `filterRules`). Free-text values are debounced (400ms) so a query only fires after the user stops typing; column/operator changes apply immediately. The filter button is a plain toggle (open when closed, close when open) |
 | Column sorting (server-side) | ✅ | Multi-column asc/desc pushed to SQL ORDER BY |
 | Column show/hide | ✅ | Toggle visibility per column |
 | Column resize (drag handle) | ✅ | Double-click to auto-fit |