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_language.py

@@ -1,11 +1,13 @@
 """Unit tests for language detection and text normalization."""
 
-from src.language import detect_language, normalize_text, SUPPORTED_LANGUAGES
+from src.language import detect_language, normalize_text
 
 
 def test_normalize_text():
     assert normalize_text("São Paulo & Petróleo") == "sao paulo & petroleo"
-    assert normalize_text("Über große Veränderungen") == "uber grosse veranderungen" or "uber" in normalize_text("Über")
+    assert normalize_text(
+        "Über große Veränderungen"
+    ) == "uber grosse veranderungen" or "uber" in normalize_text("Über")
     assert normalize_text("Crème brûlée") == "creme brulee"
 
 
@@ -24,7 +26,9 @@ def test_detect_english():
 
 
 def test_detect_spanish():
-    text = "La empresa petrolera anunció una nueva inversión en el sector energético durante este año."
+    text = (
+        "La empresa petrolera anunció una nueva inversión en el sector energético durante este año."
+    )
     lang, conf = detect_language(text)
     assert lang == "es"
     assert conf > 0.5