Fix PHP 8.4 breakage: drop deprecated mysqli::ping(), harden dep handler

The hosts were upgraded to PHP 8.4, where mysqli::ping() is deprecated
(auto-reconnect was removed in 8.2). Database::getConnection() called it on
every reused connection, and api/ticket_dependencies.php's custom error
handler treated the deprecation as a fatal 500 ('A server error occurred'),
breaking the ticket Dependencies tab.

- Database.php: remove the redundant ping()/reconnect check (connection is
  request-scoped; no liveness check needed on PHP 8.2+).
- ticket_dependencies.php: only abort on genuine errors; log notices/
  warnings/deprecations and continue, so a future deprecation can't 500 it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

api/ticket_dependencies.php

@@ -27,10 +27,19 @@ register_shutdown_function(function () {
 ini_set('display_errors', 0);
 error_reporting(E_ALL);
 
-// Custom error handler
+// Custom error handler. Only genuine errors abort the request; notices,
+// warnings and deprecations (e.g. new deprecations on a PHP upgrade) are
+// logged but must not take the endpoint down with a 500.
 set_error_handler(function ($errno, $errstr, $errfile, $errline) {
-    // Log detailed error server-side
+    // Respect the @-operator / error_reporting.
+    if (!(error_reporting() & $errno)) {
+        return false;
+    }
     error_log("PHP Error in ticket_dependencies.php: $errstr in $errfile:$errline");
+    if (!in_array($errno, [E_ERROR, E_USER_ERROR, E_RECOVERABLE_ERROR, E_PARSE], true)) {
+        // Non-fatal: log and continue.
+        return true;
+    }
     ob_end_clean();
     http_response_code(500);
     header('Content-Type: application/json');

helpers/Database.php

@@ -22,11 +22,9 @@ class Database
             self::$connection = self::createConnection();
         }
 
-        // Check if connection is still alive
+        // Note: no ping()/reconnect check — mysqli auto-reconnect was removed in
-        if (!self::$connection->ping()) {
+        // PHP 8.2 and mysqli::ping() is deprecated in 8.4. The connection is
-            self::$connection = self::createConnection();
+        // request-scoped and short-lived, so a liveness check is unnecessary.
-        }
-
         return self::$connection;
     }