feat(extractor): implement multi-engine article content extractor

- Added scripts/extract_article_contents.py for batch scraping with stealth Foxcape and triple extraction (Trafilatura, Newspaper4k, Readability)
- Created unit, integration, and E2E test suite in tests/test_extract_article_contents.py (90/90 passing)
- Updated specs/003-article-content-extractor and README.md with usage documentation and CLI contracts
- Passed ruff linting/formatting and mypy type checking cleanly

tests/test_classifier.py

@@ -1,8 +1,9 @@
 """Unit tests for deterministic classification decision logic."""
 
 import pytest
-from src.models import ECPSnapshot, RelatedEntity, DecisionCategory
+
 from src.classifier import InherenceClassifier
+from src.models import DecisionCategory, ECPSnapshot, RelatedEntity
 
 
 @pytest.fixture
@@ -23,9 +24,9 @@ def petrobras_ecp():
                 weight=0.85,
                 aliases=[],
                 scope="logistics",
-                confidence=1.0
+                confidence=1.0,
             )
-        ]
+        ],
     )