feat: Add relation extraction task

[rmitsch]

Description

Adds relation extraction task.

Related Issues

• Resolves New task: Relation extraction #231

Changes Made

• Adds relation extraction task
• Refactors schemas into separate package
• Extended GliNERBridge to support .relations

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 96.17834% with 18 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
sieves/tasks/predictive/schemas/ner.py	85.71%	5 Missing ⚠️
...es/tasks/predictive/relation_extraction/bridges.py	97.31%	4 Missing ⚠️
...ieves/tasks/predictive/relation_extraction/core.py	96.66%	2 Missing ⚠️
sieves/tasks/predictive/schemas/classification.py	81.81%	2 Missing ⚠️
...tasks/predictive/schemas/information_extraction.py	91.30%	2 Missing ⚠️
sieves/tasks/predictive/schemas/pii_masking.py	95.00%	1 Missing ⚠️
...es/tasks/predictive/schemas/relation_extraction.py	96.77%	1 Missing ⚠️
...ves/tasks/predictive/schemas/sentiment_analysis.py	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #242      +/-   ##
==========================================
+ Coverage   93.21%   93.26%   +0.04%     
==========================================
  Files          62       77      +15     
  Lines        3554     3918     +364     
==========================================
+ Hits         3313     3654     +341     
- Misses        241      264      +23     

Files with missing lines	Coverage Δ
sieves/model_wrappers/dspy_.py	84.81% <ø> (ø)
sieves/model_wrappers/gliner_.py	95.83% <100.00%> (+0.08%)	⬆️
sieves/tasks/__init__.py	100.00% <ø> (ø)
sieves/tasks/core.py	97.82% <ø> (ø)
sieves/tasks/predictive/__init__.py	100.00% <100.00%> (ø)
sieves/tasks/predictive/classification/__init__.py	100.00% <100.00%> (ø)
sieves/tasks/predictive/classification/bridges.py	94.40% <100.00%> (-1.10%)	⬇️
sieves/tasks/predictive/classification/core.py	96.64% <100.00%> (+1.35%)	⬆️
sieves/tasks/predictive/core.py	91.37% <100.00%> (-0.34%)	⬇️
sieves/tasks/predictive/gliner_bridge.py	93.01% <100.00%> (ø)
... and 35 more

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