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_adapters.py

@@ -27,7 +27,7 @@ def test_classifier_with_adapter_flags():
         target_name="TestCorp",
         aliases=["TestCorp"],
         domain="Tech",
-        anchors=["software"]
+        anchors=["software"],
     )
     res = classifier.classify(ecp, "TestCorp builds enterprise cloud software.")
     assert res.decision.value == "DIRECT_INHERENT"