OrcaSlicer: link user presets on mainframe, take its K2 Pro preset

The tracked preset had print_host 10.0.0.34:4408, which breaks CFS sync.
This is the working one from mainframe: print_host http://10.0.0.34 and
the Device UI on :4408.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

meta/hosts/mainframe.conf.yaml

@@ -20,6 +20,7 @@
     ~/.ssh/config.local:    hosts/mainframe/ssh/config.local
     ~/.config/git/identity:     hosts/mainframe/git/identity
     ~/.config/paru:             common/paru
+    ~/.config/OrcaSlicer/user:       common/OrcaSlicer/user
     ~/.config/opencode/opencode.json:    common/opencode/opencode.json
     ~/.config/opencode/personal.json:    common/opencode/personal.json
     ~/.config/opencode/work.json:        common/opencode/work.json