- client_update_scale(): re-notifies clients when output scale changes
using current_outputs max scale (avoids stale c->mon for floating windows)
- layersurface_update_scale(): same logic for layer shell surfaces (static)
- Initialize current_scale on initial commit for both surface types
- Uses 0.001f tolerance for float comparison to prevent redundant events
- Falls back to c->mon->wlr_output->scale if no current_outputs