v0.2.1

Patch — sharper definition of lint fail vs caveat. Triggered by
real-world dogfood: a <div onClick={onClose} role="dialog"> modal
backdrop fired fail for GN1210100E ("missing keyboard handler"),
but the keyboard close path lived in a sibling <button aria-label="關閉">
plus a top-of-component useHotkeys("esc", onClose) — both invisible
to single-file AST. Marking such cases fail is wrong: AST literally
cannot prove the violation, only suggest review.

Changed

• RuleMeta gains runtime_authoritative: bool = False. Rules whose
  verdict requires rendered DOM, computed CSS, focus traversal, or
  cross-file event wiring (which AST cannot reach) set this to True.
• lint runner now downgrades fail → caveat for any rule with
  runtime_authoritative=True, appending an explanatory note to the
  message: 「lint 無法跨檔/runtime 確認，請人工或 a11y-moda scan 驗證」.
  scan is unaffected — it has Playwright + computed style and can
  emit fail authoritatively for the same rules.
• Marked runtime_authoritative=True:
  • GN1210100E — onClick / mouse handler missing keyboard equivalent
    (cross-file useHotkeys / sibling button invisible to AST)
  • FA2141104E — <style> outline:none without :focus rule
    (external CSS files invisible to lint)
• Other lint rules already emit info or caveat and are unaffected.

Notes

• This is a definition fix, not a tuning knob. lint's fail
  status now means "AST proved a violation"; ambiguous cases are
  caveat regardless of runtime severity. Users who want hard
  keyboard gating in CI should run a11y-moda scan (which has the
  evidence to fail).
• Per-project --ignore / config file is not added in this patch
  (YAGNI). Will revisit if real demand surfaces.
• Dogfood after patch: light-design AAA, 135 files, 0 fail / 31 caveat
  / 0 info (real <div onClick> accordions in Footer + Faq were fixed
  to <button type="button"> between releases; Modal backdrop cleanly
  downgrades to caveat with the new note).