Organize planning documents and update README structure

- Created a new `docs/planning/` directory to better organize architecture and implementation planning documents.
- Moved existing planning documents into the new directory for improved accessibility.
- Updated `README.md` to reflect the new document structure and added references to the organized planning documents.
- Enhanced overall documentation management for easier navigation and maintenance.

docs/refactor/migrations/README.md

@@ -0,0 +1,52 @@
+# MIGRATION GUIDES
+
+**Purpose**: Step-by-step migration guides for refactoring.
+
+---
+
+## Migration Guides
+
+### Phase 0: Credit System Migration
+- [ ] Remove plan limit fields
+- [ ] Update Plan model
+- [ ] Update CreditService
+- [ ] Update AI Engine
+- [ ] Update frontend
+
+### Phase 1: Service Layer Migration
+- [ ] Create domain folders
+- [ ] Move models
+- [ ] Create services
+- [ ] Update ViewSets
+- [ ] Update imports
+
+### Phase 2: Content Model Extensions
+- [ ] Add source field
+- [ ] Add sync_status field
+- [ ] Add external_id fields
+- [ ] Create migrations
+- [ ] Update serializers
+
+### Phase 3: New Module Integration
+- [ ] Automation module
+- [ ] Linker module
+- [ ] Optimizer module
+- [ ] Site Builder module
+- [ ] Integration module
+
+---
+
+## Migration Checklist
+
+For each migration:
+- [ ] Create migration files
+- [ ] Test migrations
+- [ ] Update code references
+- [ ] Update tests
+- [ ] Update documentation
+- [ ] Deploy incrementally
+
+---
+
+**Last Updated**: 2025-01-XX
+