Add collision-aware pin 1 arrows to pinrow footprints

[seveibar]

Summary

• add a top-silkscreen pin 1 arrow to pinrow footprints, including SMD and nosquareplating variants
• choose only an outer side of the pin 1 pad and avoid the top-side pin-label direction
• reject arrow positions that overlap the reference-text bounds
• use the shared Bounds type and doBoundsOverlap helper from @tscircuit/math-utils 0.0.36
• update the direct pinrow SVG snapshots and add structural assertions for normal, no-label, round-pin-1, and SMD cases

Verification

• bun test tests/pinrow.test.ts tests/pinrow2_id1.016_od1.88_nosquareplating_pinlabeltextalignright_pinlabelorthogonal_doublesidedpinlabel_pinlabelverticallyinverted.test.ts — 29 pass
• bun run build — pass
• git diff --check — pass
• GitHub Actions build and format checks — pass

Remaining draft blocker

The visual output in tests/kicad-parity/pinrow_kicad_parity.test.ts also changes. Refreshing that snapshot requires fetching the fixture from kicad-mod-cache.tscircuit.com; the current Codex sandbox rejected that external fetch even after explicit approval. GitHub Actions confirms this is the only failing test (483 pass, 1 fail). The parity SVG snapshot still needs to be refreshed in an environment with fixture access before this PR is marked ready.