fix: SSE libera worker en 28s y detecta desconexión cada 200ms

- TTL de 28s por conexión; EventSource reconecta automáticamente (retry:3000)
- Reemplaza sleep(2) por loop usleep(200ms) para detectar pagehide rápido
- PHP-FPM workers aumentados de 5 → 20 (directo en servidor)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin/DashboardController.php

@@ -202,12 +202,11 @@ HTML;
         header('X-Accel-Buffering: no'); // disable nginx buffering
         header('Connection: keep-alive');
 
-        set_time_limit(0);
+        set_time_limit(35);
         ignore_user_abort(false);
 
         $lastId = max(0, (int)($_GET['after'] ?? 0));
 
-        // Anchor to latest ID if no after param
         if ($lastId === 0) {
             try {
                 $row = db()->query('SELECT id FROM webhook_logs ORDER BY id DESC LIMIT 1')->fetch();
@@ -215,7 +214,13 @@ HTML;
             } catch (\PDOException $e) {}
         }
 
-        while (!connection_aborted()) {
+        // Tell the client to reconnect after 3s if connection drops
+        echo "retry: 3000\n\n";
+        ob_flush(); flush();
+
+        $deadline = time() + 28; // release worker after 28s, client auto-reconnects
+
+        while (!connection_aborted() && time() < $deadline) {
             try {
                 $stmt = db()->prepare(
                     'SELECT id, event_field, from_number, contact_name,
@@ -229,7 +234,7 @@ HTML;
                     $lastId = (int)end($rows)['id'];
                     echo 'data: ' . json_encode($rows, JSON_UNESCAPED_UNICODE) . "\n\n";
                 } else {
-                    echo ": heartbeat\n\n"; // keep connection alive
+                    echo ": heartbeat\n\n";
                 }
             } catch (\PDOException $e) {
                 echo ": db-error\n\n";
@@ -237,7 +242,11 @@ HTML;
 
             ob_flush();
             flush();
-            sleep(2);
+
+            // Sleep in 200ms chunks so connection_aborted() is checked frequently
+            for ($i = 0; $i < 10 && !connection_aborted(); $i++) {
+                usleep(200000);
+            }
         }
         exit;
     }