Fix purge_nonexistent_images.bat to correctly handle images which have cyrillic (or other alphabets) in the path

[mishavoloshchuk]

I've made a fix for the purge_nonexistent_images.bat removes existing files / #20915 issue I recently added. I used Claude, because I'm not very proficient in .bat scripts. I've checked it and works completely fine and now it only removes the images that are really missing.

Here is some description from Claude itself:

The script uses for /f ... in ('sqlite3.exe ...') to iterate over query results. On Windows, this form of command substitution captures the child process output through the legacy OEM code page (e.g. CP866 for Russian locales), regardless of the active console code page set by chcp. SQLite3 outputs UTF-8 text, but for /f re-encodes it through the OEM code page, mangling any characters outside the ASCII range. The resulting garbled path string never matches a real filesystem entry, so if not exist always evaluates to true — and the image is treated as missing and scheduled for deletion, even though the underlying file is perfectly intact.

[TurboGit]

Looks ok by me but I'd like the review of a Windows expert;

@wpferguson : Can you review please? TIA

[wpferguson]

@victoryforce are you able to test this?