feat: Add recursive validation for nested SWE Common structures (Issues camptocamp#48, camptocamp#73)

- Add validateNested parameter to validateDataRecord() and validateDataArray()
- Recursively validate nested components (fields[].component, elementType)
- Validate field structure (name property requirements)
- Build proper error paths for nested errors (e.g., fields[0].component.uom)
- Support deeply nested structures (4+ levels)
- Add 30 comprehensive tests covering all nesting scenarios
- Maintain backwards compatibility (validateNested defaults to true)

This resolves the broken state from incomplete implementation and
provides full recursive validation for DataRecord and DataArray
structures as specified in SWE Common 3.0.

Author: Sam-Bolling