refactor: fix linting issues and code quality

- Fix import ordering in __init__.py
- Remove unused imports from dependencies.py
- Fix import sorting across multiple files
- Apply ruff auto-fixes

No functional changes

SKILL.md

@@ -555,6 +555,33 @@ curl http://localhost:8000/api/v1/notebooks -H "X-API-Key: your-key"
 
 ---
 
-**Skill Version:** 1.0.0  
+**Skill Version:** 1.1.0  
 **API Version:** v1  
-**Last Updated:** 2026-04-05
+**Last Updated:** 2026-04-06
+
+---
+
+## Changelog Sprint 1
+
+### 2026-04-06 - Notebook Management CRUD
+
+**Implemented:**
+- ✅ `POST /api/v1/notebooks` - Create notebook
+- ✅ `GET /api/v1/notebooks` - List notebooks with pagination
+- ✅ `GET /api/v1/notebooks/{id}` - Get notebook by ID
+- ✅ `PATCH /api/v1/notebooks/{id}` - Update notebook (partial)
+- ✅ `DELETE /api/v1/notebooks/{id}` - Delete notebook
+
+**Features:**
+- Full CRUD operations for notebook management
+- UUID validation for notebook IDs
+- Pagination with limit/offset
+- Sorting (created_at, updated_at, title)
+- Error handling with standardized responses
+- Comprehensive test coverage (97% services)
+
+**Next Sprint:**
+- Source management endpoints
+- Chat functionality
+- Content generation (audio, video, etc.)
+- Webhook system