test(ci): remove source-scanning governance gates

[jackwener]

Summary

• remove the 582-line dead-CSS regex scanner and its baseline/allowlist machinery
• remove the Story annotation presence scanner, which could not validate whether prose was true
• remove both default CI gates and keep release checks focused on stale artifacts and third-party notices
• update active CSS/Storybook guidance to assign static correctness to Biome, Knip, and typecheck, and visual correctness to rendered-surface review

Why

These scripts tested repository text rather than product behavior. Their false-positive controls and baselines added maintenance and CI cost without owning a correctness, security, data-integrity, or release-safety boundary.

Validation

• Biome on changed JSON/CSS sources
• package.json parse check
• git diff --check
• repository reference audit (excluding historical changelog/archive)
• no test suites run; CI owns execution