example: prevent focus stealing in headful mode on KDE plasma

[milahu]

recently, my scraper in headless mode is being blocked by cloudflare
(http status 403 with title Just a moment...)
so now im running my scraper in headful mode

this brought back an old problem: focus stealing

when creating new tabs, or when switching between tabs
the chromium window is grabbing focus
so when i work with some GUI app at the same time
my work is constantly interrupted

moving the chromium window to a different desktop
does not work anymore

i fixed this problem in milahu/aiohttp_chromium@2c2cfb2
by adding a new rule to ~/.config/kwinrulesrc
and reloading the rules with qdbus org.kde.KWin /KWin reconfigure

this solution is complex enough to make it worth sharing

related: KDE docs: Focus stealing prevention

todo: implement this for other window managers