feat: merge nearby same-net trace segments (#34)

[XananasX7]

/claim #34

Summary

Implements issue #34: Merge same-net trace lines that are close together (at the same Y or same X).

Adds a new merging_close_same_net_segments cleanup phase to the TraceCleanupSolver pipeline that snaps nearby parallel same-net trace segments onto a shared coordinate, eliminating the visually confusing closely-spaced parallel lines shown in the issue screenshot.

Changes

New file: lib/solvers/TraceCleanupSolver/mergeNearbySameNetSegments.ts

• Scans all interior trace segments (excluding pin-attachment endpoints to preserve routing geometry)
• Groups segments that share: the same net ID + same orientation (H or V) + overlapping free-axis range + within 0.18 units along the fixed axis
• Uses BFS clustering to handle groups of 3+ collinear close segments
• Snaps the entire group to their average fixed-axis coordinate
• Calls simplifyPath after snapping to clean up any resulting collinear points

Modified: lib/solvers/TraceCleanupSolver/TraceCleanupSolver.ts

• Added merging_close_same_net_segments as the final pipeline step after balancing_l_shapes
• The step runs once (not per-trace) via mergeNearbySameNetSegments()

New tests: tests/solvers/TraceCleanupSolver/mergeNearbySameNetSegments.test.ts

7 unit tests covering:

• Horizontal merging
• Vertical merging
• 3-trace group merging
• Different-net isolation (must NOT merge)
• Distance threshold (segments > 0.18 apart must NOT merge)
• Non-overlapping ranges (must NOT merge)
• Endpoint/pin coordinate preservation

Test Results

bun test
 77 pass
 4 skip (pre-existing)
 0 fail

bunx tsc --noEmit — clean, no errors.

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview, Comment	Jun 18, 2026 6:28pm