Add visual repros for PCB placement layer bugs

[seveibar]

Summary

• add a failing visual repro for a multi-hole footprint whose later drilled hole intersects an opposite-side courtyard
• add a failing visual repro for overlapping same-layer polygon courtyards
• label each snapshot with pcb_note_text so the missing expected error is explicit

Confirmed bugs

1. checkPcbComponentOverlap only retains the first pcb_hole for a component, so a later mechanical hole can intersect an opposite-side courtyard without an error.
2. checkCourtyardOverlap omits pcb_courtyard_polygon elements, so same-layer polygon courtyard collisions are not reported.

Both repros use test.failing so the current bugs are documented without breaking CI. A follow-up PR can implement the fixes, remove test.failing, and update the snapshots with the expected error markers.

Validation

• bun test — 143 pass
• bunx tsc --noEmit
• bun run build
• bun run format:check