refactor(downloads): extract ScanDirectoryController with clean URL route
Replaces legacy ?act=scan_dir include with ScanDirectoryController at
/downloads/scan-dir. Fixes bug where $start was used instead of $mod
for screenshot/description file handling. Removes empty includes/ directory.
/downloads/scan-dir. Fixes bug where $start was used instead of $mod
for screenshot/description file handling. Removes empty includes/ directory.