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

pyproject.toml

@@ -24,3 +24,17 @@ python_functions = ["test_*"]
 
 [tool.pyright]
 extraPaths = [".", "src"]
+
+[tool.ruff]
+line-length = 100
+target-version = "py310"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "W"]
+ignore = ["E501"]
+
+[tool.mypy]
+python_version = "3.12"
+ignore_missing_imports = true
+check_untyped_defs = true
+