feat: implement ListView Spec Protocol gap fixes (Phase 1-3)

- #39 showRecordCount: conditionally show/hide record count bar
- #24 rowHeight: add short and extra_tall mapping in ListView + bridge
- #7 sort: parse legacy string format "field desc"
- #22 description: render view description below toolbar
- #40 allowPrinting: add print button with window.print()
- #31 virtualScroll: forward flag to grid view schema
- #35 userActions: wire sort/search/filter/rowHeight to toolbar visibility
- #38 addRecord: render "+ Add Record" button from spec config
- #37 tabs: render tab bar UI for view tabs
- #9 filterableFields: restrict FilterBuilder to whitelist fields
- #8 searchableFields: scope search queries to specified fields
- #36 appearance: wire showDescription and allowedVisualizations
- #16 pageSizeOptions: add page size selector UI in status bar
- #17-21: use spec kanban/calendar/gantt/gallery/timeline configs
- #20 gallery: add typed GalleryConfig to ListViewSchema
- #21 timeline: add typed TimelineConfig to ListViewSchema
- Bridge: add short/extra_tall density mapping, filterableFields pass-through

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot