⚡️(frontend) optimize countdown check in IsIdleDisconnectModal.tsx

Using Array.includes runs in O(n) on every second of the countdown.

Replace the array with a Set to achieve O(1) lookups for better
performance.

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to
 
 - 🔒️(backend) enhance API input validation to strengthen security #1053
 - 🦺(backend) strengthen API validation for recording options #1063
+- ⚡️(frontend) optimize few performance caveats #1073
 
 ### Fixed