✨(backend) monitor throttling rate failure through sentry

Use a mixin, introduced by @lunika in the shared
backend library to monitor throttling behavior.

The mixin tracks when throttling limits are reached, sending errors to Sentry
to trigger alerts when configured. This helps detect misconfigurations,
fine-tune throttling settings, and identify suspicious operations.

This enables safely increasing API throttling limits while ensuring stability,
providing confidence that higher limits won’t break the system.

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Added
+
+- ✨(backend) monitor throttling rate failure through sentry #964
+
 ### Changed
 
 - ♿️(frontend) improve spinner reduced‑motion fallback #931