refactor: Rename Engine to ModelWrapper

[rmitsch]

Description

Renames Engine to ModelWrapper, EngineType to ModelType for better readability and easier to understand architecture.

Related Issues

• Resolves Rename Engine to ModelWrapper #224

Changes Made

Checklist

• [ ] Tests have been extended to cover changes in functionality
• Existing and new tests succeed
• Documentation updated (if applicable)
• Related issues linked

Screenshots/Examples (if applicable)

[codecov]

Codecov Report

❌ Patch coverage is 92.77778% with 13 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
sieves/model_wrappers/model_type.py	91.30%	2 Missing ⚠️
sieves/model_wrappers/huggingface_.py	75.00%	1 Missing ⚠️
sieves/model_wrappers/langchain_.py	66.66%	1 Missing ⚠️
sieves/tasks/predictive/classification/core.py	87.50%	1 Missing ⚠️
sieves/tasks/predictive/core.py	92.85%	1 Missing ⚠️
...es/tasks/predictive/information_extraction/core.py	87.50%	1 Missing ⚠️
sieves/tasks/predictive/ner/core.py	85.71%	1 Missing ⚠️
sieves/tasks/predictive/pii_masking/core.py	85.71%	1 Missing ⚠️
sieves/tasks/predictive/question_answering/core.py	85.71%	1 Missing ⚠️
sieves/tasks/predictive/sentiment_analysis/core.py	85.71%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #226      +/-   ##
==========================================
+ Coverage   92.97%   93.63%   +0.65%     
==========================================
  Files          62       62              
  Lines        3347     3348       +1     
==========================================
+ Hits         3112     3135      +23     
+ Misses        235      213      -22     

Files with missing lines	Coverage Δ
sieves/__init__.py	100.00% <100.00%> (ø)
sieves/model_wrappers/__init__.py	100.00% <100.00%> (ø)
sieves/model_wrappers/core.py	96.66% <100.00%> (ø)
sieves/model_wrappers/dspy_.py	85.96% <100.00%> (ø)
sieves/model_wrappers/gliner_.py	94.11% <100.00%> (ø)
sieves/model_wrappers/outlines_.py	80.85% <100.00%> (ø)
sieves/model_wrappers/types.py	100.00% <ø> (ø)
sieves/model_wrappers/utils.py	87.50% <100.00%> (ø)
sieves/tasks/core.py	97.82% <ø> (ø)
sieves/tasks/distillation/types.py	100.00% <ø> (ø)
... and 22 more

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