Platform-Aware User Directory Detection

What: Added cross-platform support for detecting standard user directories (Desktop, Documents, Downloads) with platform-specific environment variable handling.

How it works:

• Windows: Uses USERPROFILE environment variable
• Linux/WSL: Respects XDG directory specifications (XDG_DESKTOP_DIR, XDG_DOCUMENTS_DIR, XDG_DOWNLOAD_DIR)
• macOS: Uses standard home directory paths
• Unknown platforms: Falls back to default paths with a warning

Details:

• Automatically detects the operating system and applies appropriate path resolution
• Provides directory categorization to identify if a path is "home", "desktop", "documents", "downloads", or "other"
• Evidence: Im1() at line 301093 and Yi0() at line 455838 in v2.0.14