Refactor: Merge ObjectGrid into ObjectTable, build on data-table foundation

Per feedback from @hotlong, merged ObjectGrid functionality into ObjectTable
and refactored to use the existing data-table component as the base.

Changes:
- Removed separate ObjectGrid component
- ObjectTable now supports both 'object-table' and 'object-grid' schema types
- Leverages data-table for sorting, filtering, pagination, row selection
- Maintains all field renderers and ObjectQL integration
- Reduced code duplication and bundle size
- Single unified component for all table/grid use cases

The refactored ObjectTable automatically gets:
- Multi-column sorting
- Real-time search
- Pagination
- Row selection
- CSV export
- Column resizing
- Column reordering

Plus ObjectQL-specific features:
- Auto-generated columns from schema
- Type-aware cell rendering (20+ field types)
- Permission handling
- CRUD operations
- Data source integration

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

Author: Copilot