The List Hotkeys dialog now saves edits but was not calling
CommonSettingsChanged(HOTKEYS_CHANGED) after closing, so
ACTION_MANAGER kept stale keycode lookup maps and edited
shortcuts did not take effect until restart.
Add the HOTKEYS_CHANGED notification after the dialog closes
with OK. Add a Cancel button so users can discard accidental
edits. Exclude gesture and platform command pseudo-actions
from the Preferences panel since edits to those entries are
not persisted to disk. The List Hotkeys dialog continues to
show them for reference. Update the stale "read-only" doc
comment on DIALOG_LIST_HOTKEYS.