perf: reduce presence update frequency and fix background tab throttling (#13726)

## Description
Reduces the frequency of update_presence WebSocket calls from the live
chat widget and fixes agents appearing offline when the dashboard is in
a background tab.

## Fixes # (issue)
https://github.com/chatwoot/chatwoot/issues/13720

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)


## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

app/services/internal/remove_stale_redis_keys_service.rb

@@ -3,7 +3,7 @@ class Internal::RemoveStaleRedisKeysService
 
   def perform
     Rails.logger.info "Removing redis stale keys for account #{@account_id}"
-    range_start = (Time.zone.now - OnlineStatusTracker::PRESENCE_DURATION).to_i
+    range_start = (Time.zone.now - OnlineStatusTracker::CONTACT_PRESENCE_DURATION).to_i
     # exclusive minimum score is specified by prefixing (
     # we are clearing old records because this could clogg up the sorted set
     ::Redis::Alfred.zremrangebyscore(