feat: added business models, implemented business signup and signin

solution/config/errors.py

@@ -0,0 +1,9 @@
+from django.core.exceptions import ValidationError
+
+
+class UniqueConstraintError(Exception):
+    def __init__(self, validation_error: ValidationError) -> None:
+        self.validation_error = validation_error
+
+
+__all__ = ["UniqueConstraintError"]