Fixed the infinite installation loop.

• Added FTP/SFTP mount support, encrypted remote mount credentials, and hardened mount handling (plus email validation UI).
• Tightened CSP, fixed Ace CSP nonce handling, and added a health endpoint.
• Improved file listing UI: responsive grid/list layout, sticky list header, lazy thumbnails, and server-side sorting/pagination.
• UX tweaks: clickable breadcrumbs with separators and tree sync.
• Repo hygiene: stopped tracking writable/last_cleanup.txt.
• Version bump to 3.0.0-alpha.4.

This version introduces a complete "WeTransfer-style" file sharing system, major security hardening, and enhanced cross-platform support
for Windows/WSL environments.

📤 New: WeTransfer-style File Sharing

• External File Transfers: Users can now send files to any email address directly from eXtplorer.
• Upload Dropzone: A dedicated transfer interface with drag-and-drop support and real-time progress tracking.
• Resumable Uploads: Support for resuming interrupted transfers, ensuring reliability for large file sends.
• Expiration Management: Set custom expiration dates for transfers; files are automatically cleaned up after they expire.
• Email Notifications: Integration with SMTP to send download links directly to recipients.
• Transfer History: A new view to manage and track previously sent transfers.

🛡️ Security & Architecture

• Secure Data Storage: Migrated sensitive JSON data (Users, Shares, Logs, Mounts) into PHP-wrapped files (.php) to prevent accidental
  direct exposure via the web server.
• Poor Man's Cron: Implemented an automated background task runner that handles cleanup operations (expired shares, old logs) without requiring a system-level crontab.
• Content Security Policy (CSP): Hardened CSP headers to strictly control script and style execution.

💻 Windows & WSL Integration

• WSL Path Normalization: Automatic detection and conversion of WSL paths (e.g., /mnt/c/...) to native Windows paths (e.g., C:/...)
  when running on Windows hosts (Herd, Valet, etc.).
• Enhanced Mount UI:
  • Custom mounts now feature distinct icons (Hard Drive for local, Cloud for remote).
  • A subtle "Mount" badge in the file list identifies external directories.
  • Clean separation between system folders ("Home", "Shared") and user-added mounts.

🔧 Fixes & Polish

• Fixed a redirect loop during the installation process.

Updating from an older Version is highly recommended as this version fixes a critical vulnerability.

--- version 2.1.15 ---

• fixed a critical security issue reported by shimmeris
• PHP 8 compatibility

• fixed various security issues reported by Sander Bos
• fixed deprecated warnings on PHP 7.4