Fixes#1583 - Ubuntu 24 permission issues causing 404 errors
Changes:
- Move main public_html permission setting to END of fixPermissions function
- Ensures public_html maintains user:nogroup ownership (not user:user)
- Prevents child domain processing from interfering with main directory permissions
- Changed all async popenExecutioner calls to sync executioner calls
- Reordered operations: permissions first, then ownership
This fixes the issue where clicking "Fix Permissions" in file manager
would incorrectly change public_html group from nogroup to the user's group,
causing 404 errors on Ubuntu 24.
46e40d6822