Implement smoke test execution

**Summary**: Implement automated smoke test execution that validates basic functionality after deployments.

**Acceptance Criteria**:
- [ ] Built-in smoke test templates for common scenarios
- [ ] Custom smoke test script support and execution
- [ ] Smoke test result collection and reporting
- [ ] Smoke test failure handling and deployment cancellation
- [ ] Smoke test execution in various environments (staging, canary, production)
- [ ] Integration with testing frameworks and tools