Enhance email rendering and Jira widget functionality

- Implemented a secure rendering method for email content using a sandboxed iframe to prevent XSS attacks.
- Added thorough HTML sanitization for incoming emails to mitigate potential exploits.
- Refactored email body rendering logic to utilize a dedicated function for better readability and maintainability.
- Updated Jira widget to fetch and display dashboard data, including assigned issues and team issues, with improved filtering options.
- Enhanced the user interface of the Jira widget with a standardized control toolbar for resizing and collapsing widgets.
- Introduced inline search functionality within the Jira widget for quick ticket filtering.
- Improved error handling and logging for Jira data fetching.

config/config.php

@@ -17,6 +17,9 @@ if (!headers_sent()) {
     header('X-XSS-Protection: 1; mode=block');
     header('Referrer-Policy: strict-origin-when-cross-origin');
     header('Permissions-Policy: camera=(), microphone=(), geolocation=()');
+    if (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') {
+        header('Strict-Transport-Security: max-age=31536000; includeSubDomains');
+    }
     header_remove('X-Powered-By');
 }
 @ini_set('expose_php', 'off');