fix: Add get_current_user_optional for public endpoints

backend/auth.py

@@ -59,3 +59,26 @@ async def get_current_superuser(current_user: User = Depends(get_current_user)):
             detail="The user doesn't have enough privileges"
         )
     return current_user
+
+
+# Optional OAuth scheme that doesn't require auth
+oauth2_scheme_optional = OAuth2PasswordBearer(tokenUrl="auth/token", auto_error=False)
+
+async def get_current_user_optional(
+    token: Optional[str] = Depends(oauth2_scheme_optional), 
+    session: Session = Depends(get_session)
+) -> Optional[User]:
+    """Get current user if authenticated, otherwise return None (for public endpoints)"""
+    if not token:
+        return None
+    try:
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        email: str = payload.get("sub")
+        if email is None:
+            return None
+    except JWTError:
+        return None
+    
+    user = session.exec(select(User).where(User.email == email)).first()
+    return user
+