Fix: Profile picture upload AJAX response handling

- Add dataType: 'json' to AJAX call to properly parse JSON response
- Add Content-Type header to upload_profile_picture.php
- Add error callback with console logging for debugging
- Remove manual JSON parsing since jQuery handles it with dataType

src/processors/upload_profile_picture.php

@@ -6,6 +6,9 @@ require_once($rootPath . "/src/config/session.php");
 include_once($rootPath . '/src/config/connection.php');
 require_once($rootPath . "/src/config/functions.php");
 
+// Set JSON response header
+header('Content-Type: application/json');
+
 // Check database connection
 if (!isset($conn) || $conn === null) {
     die(json_encode(['status' => 'error', 'message' => 'Database connection failed']));