Validate LED schematic ports

[ShiboSoftwareDev]

Summary

• report a schematic error when an LED has no schematic component
• report a schematic error when LED source ports are missing from its symbol
• run the validation alongside existing schematic checks

Tests

• bun test tests/lib/check-led-schematic-ports.test.ts
• bunx tsc --noEmit
• bun run build