Martin Rys 6b25d95f77 Optimize all PNGs losslessly, sans /po, saves 360KB~ ...

*Second in series after https://invent.kde.org/plasma/plasma-workspace-wallpapers/-/merge_requests/17*

Another patch will follow from the translations SVN, after I figure out how to work with it.  

In kwin repo alone, there's another 4MB in savings with funny files like those:

```
kwin/po/ru/docs/kcontrol/windowspecific/tbird-reminder-info.png
  [oxipng] Reduced by 768.94 KB (-96.42%) from 797.52 KB
```

2024-03-16 23:53:12 +00:00

122 KiB

1313x982px

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