Fix readable labels for numbered pins

[TeedsK]

Summary

• score known pin-label vocabulary before applying the generic digit penalty, so labels such as GPIO14 and UART_TX1 can beat pin14
• make score matching case-insensitive for the existing vocabulary
• omit missing passive footprints from COMPONENT_PINS headers instead of printing undefined
• add regression coverage for digit-bearing pin labels and no-footprint passive headers

Fixes #4
/claim #4

Verification

• npx --yes bun@latest test
• ./node_modules/.bin/biome check .
• npx --yes bun@latest run build
• ./node_modules/.bin/tsc --noEmit
• git diff --check

AI-assisted with OpenAI Codex; I inspected the diff and ran the checks above before opening this PR.

[TeedsK]

All four GitHub Actions checks are green on 7696e756bffb0f48391cd12a5a7af2770596d118 (Dependency Check, Bun Test, Type Check, Format Check). This is ready for review; happy to tighten or expand the regression coverage if you want the scope adjusted.