fix: accept equally accessible connector edges

[ShiboSoftwareDev]

Summary

• treat every board edge tied for the minimum connector distance as accessible
• use a 1 µm numerical tolerance so floating-point noise does not recreate the false positive
• retain the existing warning when one edge is genuinely closer
• update the visual snapshot to remove the erroneous orientation warning

Stack

• Reproduction: test: reproduce connector corner orientation false positive #208
• This PR is based on the reproduction branch

Verification

• bun test (175 pass, 6 snapshots)
• bun run build
• bunx biome format lib/check-connector-accessible-orientation.ts tests/lib/check-connector-accessible-orientation.test.tsx