Enhanced Merge Interface with Visual Diffs

Improve the branch merge interface with better file naming (showing actual flow names instead of random IDs) and debugger like node structure showing changes between versions.

Visual Flow Comparison Implementation

• Create a mini preview version of flows for comparison

• Implement side-by-side comparison with shaded out portions to show differences

• Show nodes that don't exist in previous flow versions with visual indicators

• Support similar sync scroll between compared flows