Unbind ctrl+shift+page_up/down in Ghostty config so it doesn't interfere with tmux keybindings (#4645)

* Unbind ctrl+shift+page_up/down in Ghostty config

* Add guard clause

migrations/1770728860.sh

@@ -0,0 +1,5 @@
+echo "Unbind ctrl+shift+page_up/page_down in Ghostty so it doesn't interfere with tmux keybindings"
+
+if [[ -f ~/.config/ghostty/config ]] && ! grep -q "keybind = ctrl+shift+page_up=" ~/.config/ghostty/config; then
+  sed -i '/# Keyboard bindings/a\keybind = ctrl+shift+page_up=unbind\nkeybind = ctrl+shift+page_down=unbind' ~/.config/ghostty/config
+fi