- Add comprehensive constants.go with all string literals
- Replace hardcoded strings in sts_service.go, provider_factory.go, token_utils.go
- Update error messages to use consistent constants
- Standardize configuration field names and store types
- Add JWT claim constants for token handling
- Update tests to use test constants
- Improve maintainability and reduce typos
- Enhance distributed deployment consistency
- Add CONSTANTS.md documentation
All existing functionality preserved with improved type safety.