Motivation & Problem

In lib/features/workspace/data_grid_filter_bar.dart (lines 162–165), _onChanged immediately fires widget.onFilterChanged(val) on every single keystroke. When a user types a search term (e.g. "active_users"), this triggers 12 sequential full-dataset filter passes back-to-back in rapid succession.

Proposed Solution

1. In _DataGridFilterBarState:
   • Introduce a 150ms debounce Timer (_debounceTimer).
   • Reset the timer on each keystroke and only fire widget.onFilterChanged after the user pauses typing.
   • Immediately flush and cancel the timer on submit (Enter key) or when the widget is disposed.
2. Update data_grid_filter_bar_test.dart with tests for debounced change notifications.

Acceptance Criteria

• Rapid typing triggers only one final filter notification after the debounce delay.
• Pressing Enter immediately applies the filter without waiting for debounce.
• No timer leaks on widget disposal.