Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

schemas/user.py

@@ -0,0 +1,41 @@
+from pydantic import BaseModel, ConfigDict
+
+
+class UserCreate(BaseModel):
+    username: str
+    email: str
+    password: str
+
+
+class UserInDB(BaseModel):
+    id: int
+    username: str
+    email: str
+    role_id: int
+
+    model_config = ConfigDict(from_attributes=True)
+
+
+class UserLogin(BaseModel):
+    username: str
+    password: str
+
+
+class UserUpdate(BaseModel):
+    username: str | None = None
+    email: str | None = None
+    password: str | None = None
+
+
+class PasswordResetRequest(BaseModel):
+    email: str
+
+
+class PasswordReset(BaseModel):
+    token: str
+    new_password: str
+
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str