Closes #3201

Motivation

The current implementation uses a Debouncer with a 5-second delay to handle rapid connectivity changes. A debouncer delays every event in a burst, including the first one. This means that when the user reconnects after a brief disconnection, the app waits a full 5 seconds before reacting and resuming socket connections or syncing correspondence moves, even when the network is already stable.

Change

Replace the Debouncer with the existing Throttler from lib/src/utils/rate_limit.dart. A throttler delivers the first event in a burst immediately and suppresses subsequent events within the same time window. This preserves the protection against rapid network fluctuations while eliminating the unnecessary delay on the first reconnection event.

The throttle delay is extracted into a named constant (kConnectivityThrottleDelay) to make it configurable in tests without relying on real clock waits.

Behavior difference

Testing

Existing tests pass. No new dependencies introduced. Throttler already exists in lib/src/utils/rate_limit.dart.

Note: This contribution was made as part of a mobile application development course. The change was identified through a micro-optimization audit of the codebase, where the behavioral difference between Debouncer and Throttler was analyzed as a real-world example of rate-limiting patterns in a production Flutter app.