Fix test discovery and coverage for python_pkg modules

- Update pytest testpaths: PYTHON -> python_pkg (PYTHON was empty)
- Add missing __init__.py to: stockfish_analysis, screen_locker, extract_links
- Now coverage correctly reports 0% for untested modules:
  - screen_locker/screen_lock.py (279 stmts, 0% coverage)
  - stockfish_analysis/analyze_chess_game.py (327 stmts, 0% coverage)

pyproject.toml

@@ -181,7 +181,7 @@ exclude_dirs = ["tests", ".venv", "Bash/ffmpeg-build", "python_pkg/lichess_bot/.
 # PYTEST - Testing framework configuration
 # ============================================================================
 [tool.pytest.ini_options]
-testpaths = ["tests", "PYTHON", "articles"]
+testpaths = ["tests", "python_pkg", "articles"]
 python_files = ["test_*.py", "*_test.py"]
 python_classes = ["Test*"]
 python_functions = ["test_*"]

python_pkg/extract_links/__init__.py

@@ -0,0 +1 @@
+"""Extract links module."""

python_pkg/screen_locker/__init__.py

@@ -0,0 +1 @@
+"""Screen locker module."""

python_pkg/stockfish_analysis/__init__.py

@@ -0,0 +1 @@
+"""Stockfish analysis module."""