FHIR support (#12)

* Add FHIR resolver example script

- Introduced a new script `fhir_resolver.py` that demonstrates FHIR-to-OMOP concept resolution using the OMOPHub SDK.
- The script includes examples for resolving SNOMED, ICD-10-CM, LOINC, RxNorm codes, and text-only semantic searches.
- Added functionality for direct standard lookups, non-standard code mapping, and Phoebe recommendations.
- Supports batch resolution and asynchronous usage for improved performance.

* Implement FHIR type interoperability and client helpers

- Added support for FHIR type interoperability in the resolver, allowing acceptance of various Coding-like inputs (dicts, TypedDicts, and objects with .system/.code attributes).
- Introduced new FHIR type definitions (`Coding`, `CodeableConcept`) and runtime-checkable protocols (`CodingLike`, `CodeableConceptLike`) for structural matching.
- Implemented FHIR client interop helpers to configure external libraries (`fhirpy`, `fhir.resources`) with OMOPHub's FHIR Terminology Service.
- Enhanced `Fhir.resolve`, `Fhir.resolve_batch`, and `Fhir.resolve_codeable_concept` methods to accept mixed input types.
- Updated documentation and examples to reflect new functionalities and usage patterns.
- Added comprehensive unit and integration tests to validate new features and ensure compatibility.

* Refactor examples to remove hardcoded API keys

- Updated example scripts.
- Adjusted search and resolution methods in examples to reflect the new API response structures, ensuring consistency across examples.
- Improved documentation and comments in example scripts for clarity and better user guidance.

Add FHIR resolver example script (#11)

- Introduced a new script `fhir_resolver.py` that demonstrates FHIR-to-OMOP concept resolution using the OMOPHub SDK.
- The script includes examples for resolving SNOMED, ICD-10-CM, LOINC, RxNorm codes, and text-only semantic searches.
- Added functionality for direct standard lookups, non-standard code mapping, and Phoebe recommendations.
- Supports batch resolution and asynchronous usage for improved performance.

Co-authored-by: alex-omophub <[email protected]>

Update CHANGELOG for v1.5.1 release

Prep for v1.5.0 release

Prepare v1.4.1 release

Co-Authored-By: Claude Opus 4.6 <[email protected]>

Increase rate limit delay in integration tests from 1 second to 2 sec…

…onds for improved test reliability.

Prepare release v1.3.1

Improved tests

Update CHANGELOG for v0.2.0: add parameters to `concepts.get_by_code(…

…)` for synonyms and relationships, and update User-Agent header format.

Import builtins conditionally in type checking for improved clarity