fix(terminal): add WS heartbeat and fix proxy idle disconnects

Proxies (Cloudflare, nginx) drop idle WebSocket connections before the
application notices, leaving clients typing into dead sockets.

- Add server-side ping/pong heartbeat (30s) in terminal-server.js;
  terminate unresponsive clients instead of letting connections go stale
- Move client keepAlive interval start to the connect event so it
  restarts correctly after reconnects
- Remove hidden-tab keepalive short-circuit — server pings now own
  liveness; suppressing client pings while hidden masked proxy drops
- Fix clearAllTimers to use clearTimeout for one-shot timers
- On visibility resume, probe with a 5s timeout instead of the default
  35s so half-open sockets are detected quickly
- Bump coolify-realtime to 1.0.14 across all compose files

config/constants.php

@@ -4,7 +4,7 @@ return [
     'coolify' => [
         'version' => '4.0.0',
         'helper_version' => '1.0.13',
-        'realtime_version' => '1.0.13',
+        'realtime_version' => '1.0.14',
         'self_hosted' => env('SELF_HOSTED', true),
         'autoupdate' => env('AUTOUPDATE'),
         'base_config_path' => env('BASE_CONFIG_PATH', '/data/coolify'),