fix(walkthrough): tighten License section spacing for verifier compatibility

fix(license): switch from Apache 2.0 to MIT to satisfy hackathon rule

docs: snapshot competition requirements as authoritative section in CLAUDE.md

fix: composite alpha onto white before VLM round-trip

feat: end-to-end smoke test + gold-set accuracy harness

docs: fill in GitHub + HF Space URLs in CLAUDE.md

fix: shorten README short_description to <60 chars (HF Space requirement)

chore: drop Build-in-Public extra challenge

feat: SignBridge initial scaffold + tests