Add EXIF writing and machine metadata support

tests/test_settings.py

@@ -60,6 +60,8 @@ def test_load_config_defaults(tmp_path):
     assert cfg["timeout"] == 60
     assert cfg["request_delay"] == 0.5
     assert cfg["output_dir"] == "archives"
+    assert cfg["write_exif"] is True
+    assert cfg["machine_metadata"] == {}
 
 
 def test_load_config_overrides(tmp_path):