feat: add suppression hygiene checks

[bntvllnt]

Summary

• add suppression ledger for active/stale ci-ignore-* and @expected-unused directives
• add no-stale-suppressions warning findings and summary counts for CI gating
• add JSDoc cleanup semantics: @public protects exported type declarations; @internal remains checkable
• update schema, docs, llms files, and roadmap CH-P1-06 status

Tests

• pnpm lint
• pnpm typecheck
• pnpm build
• pnpm test (32 files, 462 tests)
• pnpm verify:cli-real (59 pass, 0 fail)
• git diff --check

Review

• /tmp/code-review-suppression-hygiene.json
• CLEAN verdict; main risk is additive CheckResult/CheckSummary shape change on high-blast src/types/index.ts