Design layer configuration schema for `azure.yaml`

**Summary**: Define the YAML schema structure for specifying infrastructure layers in the azure.yaml configuration file, including layer metadata, provider information, and dependencies.

**Acceptance Criteria**:
- [ ] YAML schema supports layer name, provider type, and file path specification
- [ ] Schema validation for layer configuration
- [ ] Support for layer dependencies and deployment order
- [ ] Backward compatibility with existing azure.yaml format
- [ ] Schema documentation and examples
- [ ] JSON schema definition for IDE support