Stop world-writable browser policy directories

Chromium managed policy is mandatory for every profile. World-writable
dirs let any local uid plant policy, including force-installed
extensions. Write goes through the omarchy-browser-policy group at 2775
so theme colour still works without other-write.

install/config/theme-system.sh

@@ -6,10 +6,6 @@ ln -snf /usr/share/icons/Adwaita/symbolic/actions/go-next-symbolic.svg \
           /usr/share/icons/Yaru/scalable/actions/go-next-symbolic.svg
 gtk-update-icon-cache /usr/share/icons/Yaru &>/dev/null || true
 
-# Chromium policy directory for theme
-mkdir -p /etc/chromium/policies/managed
-chmod a+rw /etc/chromium/policies/managed
-
 # Default Chromium to follow system appearance ("device") instead of dark
 mkdir -p /usr/lib/chromium
 echo '{"browser":{"theme":{"color_scheme":0,"color_scheme2":0}}}' > \