Fixes #1698.

Summary

• add explicit allowlist/blocklist wording for the sender rules menu
• keep the existing allow/block actions unchanged
• cover the action labels with a focused component spec

Tests

• npx tsc -p src/tsconfig.spec.json --noEmit
• npx eslint src/app/mailviewer/singlemailviewer.component.ts src/app/mailviewer/singlemailviewer.component.spec.ts
• npm run lint (passes with existing warnings)
• npm run policy (passes; reports existing historical commit-message notes)
• npm run build (passes with existing Angular/CommonJS warnings)
• npm run test -- --watch=false --browsers=ChromeHeadless --include=src/app/mailviewer/singlemailviewer.component.spec.ts (blocked: ChromeHeadless launcher is not registered in this checkout)

Used OpenAI Codex to inspect the issue, implement the patch, and run local validation.