docs: add research assets, screenshots and guides

Include supplementary documentation, research notes on Lexical/UX, and setup guides.

docs/prd.md

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+# Enchun.tw Website Migration Brownfield PRD
+
+**Version:** v4
+**Status:** Active
+**Created:** 2025-01-29
+**Project:** Enchun CMS System Migration
+
+## 📑 Document Structure
+
+This PRD is organized into the following sections:
+
+1. [Project Analysis and Context](./prd/01-project-analysis.md)
+   - Existing Project Overview
+   - Documentation Analysis
+   - Enhancement Scope Definition
+   - Goals and Background Context
+
+2. [Requirements](./prd/02-requirements.md)
+   - Functional Requirements (FR1-FR12)
+   - Non-Functional Requirements (NFR1-NFR10)
+   - Compatibility Requirements (CR1-CR5)
+
+3. [User Interface Enhancement Goals](./prd/03-ui-enhancement-goals.md)
+   - Integration with Existing UI
+   - Modified/New Screens and Views
+   - UI Consistency Requirements (UC1-UC8)
+
+4. [Technical Constraints and Integration Requirements](./prd/04-technical-constraints.md)
+   - Existing Technology Stack
+   - Integration Approach
+   - Code Organization and Standards
+   - Deployment and Operations
+   - Risk Assessment and Mitigation
+
+5. [Epic and Story Structure](./prd/05-epic-stories.md)
+   - Epic Approach
+   - Detailed User Stories with Acceptance Criteria
+
+## 🎯 Executive Summary
+
+This document defines the requirements for migrating the existing `enchun.tw` website from Webflow CMS to a modern architecture using Payload CMS and Astro (SSR). The migration preserves all content, maintains SEO value, and improves performance while adding a robust authentication system.
+
+**Key Objectives:**
+- Migrate 7 main pages + 35+ blog articles
+- Implement Payload CMS with built-in authentication
+- Achieve Lighthouse 95+ performance scores
+- Deploy to Cloudflare infrastructure
+- Maintain 95%+ visual fidelity to original design
+
+## 📊 Migration Priority Matrix
+
+| Priority | Pages | Estimated Time |
+|----------|-------|----------------|
+| **P0** | Header, Footer, Home, Contact | 19-28h |
+| **P1** | About, Solutions, Teams, Portfolio | 24-32h |
+| **P2** | Blog system (list, categories, articles) | 30-44h |
+
+## 🚀 Quick Links
+
+- **Original PRD:** [`PRD.md`](../PRD.md) (contains legacy Auth.js references - see this document for corrections)
+- **CMS Structure:** [`../cms_structure.md`](../cms_structure.md)
+- **Research Source:** [`../research/www.enchun.tw/`](../research/www.enchun.tw/)
+
+---
+
+**Document maintained by:** Product Manager (PM Agent)
+**Last Updated:** 2025-01-29