feat: add mapper for student and it loads

backend/model/student.py

@@ -20,3 +20,6 @@ class Student:
         if isinstance(other, Student):
             return self.id == other.id
         return False
+
+    def __hash__(self) -> int:
+        return hash(self.id)

backend/model/tribe.py

@@ -26,8 +26,5 @@ class Tribe:
             return self.name == other.name
         return False
 
-    def __repr__(self) -> str:
-        return f"<Tribe {self.name=}>"
-
     def to_dict(self) -> dict:
         return {"name": self.name, "level": self.level}