[r4victor]

• Check src/tests/_internal/core with pyright.
• Add IncludeExcludeStrDictType and use it for the core/compatibility excludes, which are always keyed by field names; nested values can still be keyed by int.
• Make the backend tests' _compute_with_mocked_api_client() helpers return the mocked API client, so tests configure a MagicMock rather than the typed client attribute.
• Use model_validate() for shorthand test inputs like ResourcesSpec(disk="100GB.."), and construct expected values directly so the parser isn't tested against itself.
• Build real offers and instance configurations in the verda tests instead of SimpleNamespace fakes.
• Narrow union and optional results in tests with isinstance and is not None asserts.
• Pass Requirements instead of None to get_offers_by_requirements() in the seeweb tests.