Split the auth module into hashing, password policy, passwords and login

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

max/auth/password_policy.py

@@ -0,0 +1,13 @@
+from .hashing import is_password_too_long
+
+PASSWORD_TOO_LONG_MESSAGE = (
+    "The password must be at most 72 bytes long "
+    "(72 characters, fewer with umlauts or special characters)"
+)
+
+
+def validate_password(password: str):
+    """Returns the (untranslated) error message, or None if the password is valid"""
+    if is_password_too_long(password):
+        return PASSWORD_TOO_LONG_MESSAGE
+    return None