Add same-net trace consolidation phase

[ColumbusLabs]

Summary

• add a same-net trace consolidation phase after trace cleanup and before final label placement
• preserve pin anchors and existing trace metadata while snapping safe same-net segments onto a shared X/Y coordinate
• reject unsafe snaps that would create diagonals, chip collisions, or different-net intersections
• restore final visualization metadata for stable SVG snapshots while keeping snapshot changes focused on geometry

Tests

• ~/.bun/bin/bun test tests/solvers/SameNetTraceConsolidationSolver/SameNetTraceConsolidationSolver.test.ts
• ~/.bun/bin/bun test tests/solvers/SchematicTracePipelineSolver/SchematicTracePipelineSolver_sameNetTraceConsolidationPhase.test.ts tests/examples/example37.test.ts
• ~/.bun/bin/bun test
• ~/.bun/bin/bunx tsc --noEmit
• ~/.bun/bin/bun run format:check
• ~/.bun/bin/bun run build

Review-only PR before upstream submission.