Create strategy execution framework

**Summary**: Build the core execution framework that orchestrates deployment strategies with lifecycle management and error handling.

**Acceptance Criteria**:
- [ ] Strategy execution engine with pluggable strategy implementations
- [ ] Lifecycle management (initialize, execute, validate, cleanup)
- [ ] Error handling and recovery mechanisms per strategy
- [ ] Progress tracking and status reporting during strategy execution
- [ ] Resource state management and coordination
- [ ] Integration with existing azd deployment pipeline