feat: basic RBAC support

backend/constants.py

@@ -7,7 +7,12 @@ class MESSAGES(str, Enum):
 
 class ERROR_MESSAGES(str, Enum):
     DEFAULT = lambda err="": f"Something went wrong :/\n{err if err else ''}"
+    INVALID_TOKEN = (
+        "Your session has expired or the token is invalid. Please sign in again."
+    )
+    INVALID_CRED = "The email or password provided is incorrect. Please check for typos and try logging in again."
     UNAUTHORIZED = "401 Unauthorized"
+    ACCESS_PROHIBITED = "You do not have permission to access this resource. Please contact your administrator for assistance."
     NOT_FOUND = "We could not find what you're looking for :/"
     USER_NOT_FOUND = "We could not find what you're looking for :/"
     MALICIOUS = "Unusual activities detected, please try again in a few minutes."