Fixed a QML property binding timing issue where dynamically created timers
and processes for per-monitor wallpaper cycling were being assigned to
properties and then immediately read back, which could return undefined
or stale values.
The fix stores the created object in a local variable before assigning
to the property map, ensuring a valid reference is always used.
Affected functions:
- startMonitorCycling() - timer creation
- cycleToNextWallpaper() - process creation
- cycleToPrevWallpaper() - process creation
