refactor: [#281] replace to_environment_params with ValidatedEnvironmentParams TryFrom

- Create ValidatedEnvironmentParams struct with 9 named fields
- Implement TryFrom<EnvironmentCreationConfig> for ValidatedEnvironmentParams
- Update handler and config_loader to use new pattern
- Remove deprecated to_environment_params() method
- Update all tests and documentation

This eliminates the Clippy warning about tuple complexity and provides
a more idiomatic, self-documenting API following the established TryFrom
pattern used for other DTO conversions.

Author: josecelano