fix: address raycast store review feedback

[suregoodru]

Summary

• apply the outstanding Raycast Store review fixes to the canonical WordingKit repository
• preserve completed rewrites when usage metadata cannot be recorded
• prevent cancelled rewrites from reaching later clipboard delivery stages
• isolate per-mode usage timestamps from the shared settings document to avoid cross-command lost updates
• add regression coverage for Store metadata, validation, cancellation, and concurrent storage behavior

Verification

• npm test — 69 tests passed
• npx tsc --noEmit
• npm run lint
• npm run build
• git diff --check

Limitations

• manual rewrite/paste verification in the Raycast UI was not repeated for this follow-up