Break the legacy PRDEditor.jsx monolith into a feature-based TypeScript architecture under src/components/prd-editor while keeping behavior parity and readability.
Key changes:
- Replace PRDEditor.jsx with a typed orchestrator component and a compatibility export bridge at src/components/PRDEditor.tsx.
- Split responsibilities into dedicated hooks: document loading/init, existing PRD registry fetching, save workflow with overwrite detection, and keyboard shortcuts.
- Split UI into focused view components: header, editor/preview body, footer stats, loading state, generate-tasks modal, and overwrite-confirm modal.
- Move filename concerns into utility helpers (sanitize, extension handling, default naming) and centralize template/constants.
- Keep component-local state close to the UI that owns it (workspace controls/modal toggles), while shared workflow state remains in the feature container.
- Reuse the existing MarkdownPreview component for safer markdown rendering instead of ad-hoc HTML conversion.
- Update TaskMasterPanel integration to consume typed PRDEditor directly (remove any-cast) and pass isExisting metadata for correct overwrite behavior.
- Keep all new/changed files below 300 lines and add targeted comments where behavior needs clarification.
Validation:
- npm run typecheck
- npm run build
