Add unit tests for property type validation

[Shubh-Raj]

Description

The current test suite lacks coverage for property type validation. The validate_*_property functions in model_manager/mod.rs (lines 214-236) have no dedicated tests.

Proposed Tests

1. test_boolean_property_type_mismatch - Should fail when string passed where boolean expected
2. test_integer_property_type_mismatch - Should fail when string passed where integer expected
3. test_array_property_expects_array - Should fail when non-array passed for isArray: true property
4. test_optional_property_can_be_missing - Optional properties should not cause validation failure when absent

Benefits

• Improved test coverage for core validation logic
• Catches regressions in property type checking
• Documents expected behavior