Enhance security and localization features across the application

- Added rehype-sanitize plugin to the markdown configuration for improved security against XSS attacks.
- Updated environment variables in the codebase to include new configurations for SMTP and monitoring.
- Implemented secure headers in server and Nginx configurations to bolster security.
- Refactored email handling to prevent spoofing by ensuring safe sender addresses.
- Improved localization by updating language persistence and button components for better user experience.
- Enhanced the uptime API and contact form with better error handling and logging practices.
- Updated dependencies in package.json and package-lock.json for better performance and security.

src/env.d.ts

@@ -5,7 +5,17 @@
 /// <reference types="../vendor/integration/types.d.ts" />
 
 interface ImportMetaEnv {
-  readonly GITLAB_TOKEN: string;
+  readonly GITEA_TOKEN?: string;
+  readonly UPTIME_KUMA_URL?: string;
+  readonly SITE?: string;
+  readonly SMTP_HOST?: string;
+  readonly SMTP_PORT?: string;
+  readonly SMTP_USER?: string;
+  readonly SMTP_PASS?: string;
+  readonly ADMIN_EMAIL?: string;
+  readonly WEBSITE_NAME?: string;
+  readonly GEMINI_API_KEY?: string;
+  readonly MANUAL_REVIEW_SECRET?: string;
 }
 
 interface ImportMeta {