chore: Add pytest configuration and update CI to skip DeepFace during tests

This commit introduces a new `pytest.ini` configuration file for backend tests, specifying test discovery patterns and output options. Additionally, the CI workflow is updated to set an environment variable that prevents DeepFace and TensorFlow from loading during tests, avoiding illegal instruction errors on certain CPUs. The face service and pose detection modules are modified to conditionally import DeepFace and RetinaFace based on this environment variable, enhancing test reliability. These changes improve the testing setup and contribute to a more robust CI process.

pytest.ini

@@ -0,0 +1,27 @@
+[pytest]
+# Pytest configuration for PunimTag backend tests
+
+# Test discovery patterns
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+
+# Test paths
+testpaths = tests
+
+# Output options
+addopts = 
+    -v
+    --strict-markers
+    --tb=short
+    --disable-warnings
+
+# Markers
+markers =
+    slow: marks tests as slow (dummy marker for future use)
+    integration: marks tests as integration tests (dummy marker for future use)
+
+# Environment variables set before test collection
+# SKIP_DEEPFACE_IN_TESTS is set in conftest.py to prevent DeepFace/TensorFlow
+# from loading during tests (avoids illegal instruction errors on some CPUs)
+