fix: validate routed trace source attribution

[seveibar]

Summary

• Validate an autorouter-supplied source_trace_id against explicit PCB endpoint connectivity before preserving it.
• Use connectivity-map keys for the fast path and fall back to the full source connectivity map when keys are unavailable.
• Add a regression where a GND PCB trace is incorrectly pre-attributed to a VBAT source trace.

This prevents future Circuit JSON builds from emitting the conflicting attribution observed in https://tscircuit.com/seveibar/nrf52810#pcb.

Verification

• bun test tests/repros/repro-routed-trace-attribution-rejects-conflicting-source-trace.test.tsx tests/repros/repro-routed-trace-attribution-ignores-opposite-layer-pad.test.tsx
• bunx tsc --noEmit
• bun run build
• bunx biome format .

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
tscircuit-core-benchmarks	Ready	Preview	Aug 22, 2026 10:34pm

[github-actions]

This PR has been automatically marked as stale because it has had no recent activity. It will be closed if no further activity occurs.