Add Auth schemas

backend/app/schemas/auth.py

@@ -0,0 +1,11 @@
+"""Authentication schemas."""
+from pydantic import BaseModel
+
+class Token(BaseModel):
+    """Token response schema."""
+    access_token: str
+    token_type: str
+
+class TokenData(BaseModel):
+    """Token data schema."""
+    username: str | None = None