feat: implement SameNetTraceMergeSolver to snap and fuse collinear traces (#34)

[IssacDanny]

/claim #34

Intuition:
Schematic traces belonging to the same net often run parallel and
close together. Snapping these to a common axis and fusing them into a single
path improves schematic readability and reduces the total number of trace
objects in the final layout.

Approach:
The SameNetTraceMergeSolver is implemented using a Hylomorphism pattern
to separate data deconstruction from merging logic:

1. Deconstruction (Coalgebra): The solver deconstructs SolvedTracePath objects
   into individual segments. Each segment is tagged with its NetId and
   orientation (Horizontal/Vertical).
2. Transformation (Algebra - Snapping): Segments are grouped by NetId and
   sorted by their fixed coordinate. A greedy clustering algorithm identifies
   segments within a 0.1 unit tolerance that share an overlapping range. These
   clusters are snapped to their calculated average coordinate.
3. Reconstruction (Algebra - Fusion): A fixed-point iteration joins collinear
   segments that touch at their endpoints. This collapses fragmented segments
   back into a minimal set of continuous SolvedTracePath objects.
4. Simplification: Redundant collinear points created during the snapping
   process are removed using simplifyPath.

Complexity:

• Time Complexity: O(N log N), where N is the total number of segments across
  all traces. The complexity is dominated by the sorting step required for
  greedy clustering.
• Space Complexity: O(N), as intermediate segment references are stored on the
  heap to ensure O(1) stack depth.

Verification Results

• Verified in the playground that parallel GND/VCC traces snap and fuse into
  single paths.
• Updated 8 visual snapshots to reflect the improved trace geometry. All 61
  tests are passing (with 4 expected skips).

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview, Comment	May 12, 2026 8:37pm