Description

Refactored the nugget optimization functionality into a dedicated module for better organization and reusability. The PR extracts the optimization logic from compute_API.py into a new optimize_nuggets module with improved structure and cleaner implementation. It also adds a new API function optimize_nuggets that allows optimizing specific structural groups rather than the entire model.

The PR also includes code reorganization, moving the _LoadDEMArtificial class from create_topography.py to topography.py where it's more logically placed, and fixing import paths throughout the codebase.

Relates to #optimization-refactoring

Checklist

• My code uses type hinting for function and method arguments and return values.
• I have created tests which cover my code.
• The test code either 1. demonstrates at least one valuable use case (e.g. integration tests)
  or 2. verifies that outputs are as expected for given inputs (e.g. unit tests).
• New tests pass locally with my changes.