Swimlanes

Connection Lines (aka "Swimlanes") is a feature that visualizes dependencies between queries, expressions, and transformations in the panel editor pipeline. When a query, expression, or tranasformation is selected, a vertical line appears on the right side showing which items reference each other. ### Implementation Files - ConnectionLines.tsx (198 lines) - SVG rendering component - QueryTransformList.tsx (lines 186-229) - Connection detection logic - Integration with drag-and-drop and selection state This feature in the hackathon branch is _really_ hacky. The logic and approach need to be refined massively. It also only addresses connections between queries and expressions, so we'll need to extend the logic to include transformations. ### Acceptance Criteria - [ ] Refine and refactor logic. It's brittle right now. - [ ] Add error boundary - [ ] Add unit tests - [ ] Performance test with 30+ cards - [ ] Manual testing with various expression types