macOS Temp Folder Sandbox Support

What: Automatic sandbox permissions for macOS system temp directories.

Details:

• Detects macOS temp folders at /var/folders/XX/YYYYYYYY/T/
• Automatically allows write access to detected temp directories
• Handles both /var/folders/ and /private/var/folders/ paths (symlink variants)
• Enables seamless screenshot workflows where macOS saves screenshots to temp folders
• No user configuration required - works automatically when TMPDIR environment variable is set
• Evidence: y19() detection function at line 363940, integrated into j19() at line 363726