Dispatches kglobalshortcutsrc identifiers through the kglobalaccel D-Bus
service instead of the schema-backed or freeform rc-file paths. Verified
manually against the live session (per the spec's testing decision, this
mechanism is excluded from the automated suite); switched to the
shortcutKeys/defaultShortcutKeys/setShortcutKeys D-Bus methods after the
spec's originally-named shortcut/defaultShortcut/setShortcut proved to
return stale data on the live system. Moves Lock Session off Meta+L to
Meta+X as the real-world validation, tracked in the manifest and recorded
in keybindings.md.
