Improve PCB overlap error messages and add sample-style repro test

[seveibar]

Motivation

• Make PCB footprint overlap diagnostics more actionable by including clearer identifiers and spatial context for overlapping elements to simplify debugging of errors like pcb_smtpad element overlaps with pcb_smtpad element.
• Provide a small, reproducible test in the same JSX/style as the provided sample circuit to ensure the new message format is emitted and rendered.

Description

• Added a formatOverlapElementDescription helper that produces a descriptive string for an overlapped element including readable name + element id, owning component (when present), port (when present), and center coordinates in millimeters, and wired it into the overlap error message creation in checkPcbComponentOverlap.
• Expanded imports to use getReadableNameForComponent and getReadableNameForPort and replaced the terse overlap message with the new detailed format.
• Added a repro test tests/lib/check-pcb-component-overlap/test.tsx that renders a small board/chip footprint (sample003-style) to reproduce a pcb_smtpad overlap and added/updated SVG snapshots to assert the error is drawn.

Testing

• Ran BUN_UPDATE_SNAPSHOTS=1 bun test tests/lib/check-pcb-component-overlap and the suite passed (4 tests, snapshots refreshed for overlap cases).
• Ran BUN_UPDATE_SNAPSHOTS=1 bun test ./tests/lib/check-pcb-component-overlap/test.tsx and the new repro test passed and wrote the snapshot (1 pass).
• Ran bunx tsc --noEmit for type-checking and it completed successfully with no errors.
• Ran bun run format, which completed successfully but reported Biome size warnings for large fixture JSON files while formatting the repository.

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Codex Task

[tscircuitbot]

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PR Rating: ⭐⭐
Impact: Minor

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