Add pytest config and key derivation tests

src/tests/test_key_derivation.py

@@ -0,0 +1,18 @@
+import logging
+import pytest
+from utils.key_derivation import derive_key_from_password
+
+
+def test_derive_key_deterministic():
+    password = "correct horse battery staple"
+    key1 = derive_key_from_password(password, iterations=1)
+    key2 = derive_key_from_password(password, iterations=1)
+    assert key1 == key2
+    assert len(key1) == 44
+    logging.info("Deterministic key derivation succeeded")
+
+
+def test_derive_key_empty_password_error():
+    with pytest.raises(ValueError):
+        derive_key_from_password("")
+    logging.info("Empty password correctly raised ValueError")