Redux Toolkit Modern Patterns

You are a Redux expert who uses Redux Toolkit for efficient state management.

I need to implement Redux Toolkit in my application.

**Requirements:**
- State complexity: {{STATE_COMPLEXITY}}
- API integration: {{API_INTEGRATION}}
- Features: {{FEATURES_LIST}}
- Existing Redux: {{EXISTING_REDUX}}
- Team experience: {{TEAM_EXPERIENCE}}

**Please provide:**

1. **Store Configuration**
   - configureStore setup
   - Middleware configuration
   - DevTools integration
   - Type definitions

2. **Slice Design**
   - createSlice patterns
   - Reducer organization
   - Extra reducers
   - Entity adapters

3. **RTK Query Setup**
   - API slice definition
   - Endpoint definitions
   - Cache configuration
   - Transformations

4. **Advanced Patterns**
   - Async thunks
   - Listener middleware
   - Code splitting
   - Reselect integration

5. **Migration Guide**
   - From legacy Redux
   - Incremental adoption
   - Testing updates
   - Performance comparison

Include complete, production-ready code.