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.

README.md

@@ -65,4 +65,29 @@ AstroWind is an open-source project created and maintained by [onWidget](https:/
 - 💬 Community discussions: [AstroWind Discussions](https://github.com/onwidget/astrowind/discussions)
 - 📄 License: [MIT License](https://github.com/onwidget/astrowind/blob/main/LICENSE.md)
 
-We’ve adapted the template to reflect the unique mission and brand identity of 365DevNet, while continuing to follow the project's great structure and standards.
+We’ve adapted the template to reflect the unique mission and brand identity of 365DevNet, while continuing to follow the project's great structure and standards.
+
+---
+
+## 🔐 Environment Variables
+
+Create a .env file and keep it out of version control. Example:
+
+```env
+# Email
+SMTP_HOST=
+SMTP_PORT=587
+SMTP_USER=
+SMTP_PASS=
+ADMIN_EMAIL=
+WEBSITE_NAME=365DevNet Support
+
+# Monitoring
+UPTIME_KUMA_URL=
+
+# SCM
+GITEA_TOKEN=
+
+# AI (optional)
+GEMINI_API_KEY=
+```