feat: implement API security measures phase 1

api/accounts/throttles.py

@@ -0,0 +1,12 @@
+from rest_framework.throttling import SimpleRateThrottle
+
+
+class UserRateThrottle(SimpleRateThrottle):
+    """Throttle authenticated requests by user ID."""
+
+    scope = "user"
+
+    def get_cache_key(self, request, view):
+        if request.user and request.user.is_authenticated:
+            return self.cache_format % {"scope": self.scope, "ident": request.user.pk}
+        return None  # AnonRateThrottle handles anonymous requests