fix(tests): correct build path in test_article_create_manual

Route writes to BUILD_DIR/<language>/<slug>.html but test was checking
BUILD_DIR/<slug>.html (missing language subdirectory). Default language
is "en" so correct path is BUILD_DIR/en/manual-art.html.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/tests/test_content.py

@@ -1182,8 +1182,8 @@ class TestAdminArticles:
         assert row is not None
         assert row["title"] == "Manual Article"
 
-        # Build file created
-        build_path = BUILD_DIR / "manual-art.html"
+        # Build file created at BUILD_DIR/<language>/<slug>.html (language defaults to "en")
+        build_path = BUILD_DIR / "en" / "manual-art.html"
         try:
             assert build_path.exists()
             content = build_path.read_text()