Add Olmo3 architecture adapter tests

[RecreationalMath]

Description

Adds the minimal unit test for Olmo3ArchitectureAdapter under tests/unit/model_bridge/supported_architectures/.

The adapter body is pass. It inherits its config, component mapping, and weight conversions unchanged from Olmo2ArchitectureAdapter (covered by test_olmo2_adapter.py). Per the unit-test guide ("for a pure-pass subclass adapter… the subclass needs exactly one test, that it is a subclass"), the only contract this subclass owns is the subclass relationship itself.

The single test asserts issubclass(Olmo3ArchitectureAdapter, Olmo2ArchitectureAdapter). Modeled on the existing test_llava_next_adapter.py precedent.

Contributes to #1302 (Olmo3 checkbox).

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have not rewritten tests relating to key interfaces which would affect backward compatibility