Side panel devices show a thin progress bar below each drive name,
proportional to disk usage. Bar turns red when usage exceeds 90%.
The computer:// icon view also shows usage bars under volume names.
New files:
- thunar-shortcuts-progress-renderer.c/.h: custom cell renderer
(extends GtkCellRendererText) that draws text + usage bar
Modified:
- thunar-shortcuts-model: added USAGE_PERCENT column
- thunar-shortcuts-view: uses progress renderer instead of plain text
- thunar-text-renderer: added usage-percent property with bar drawing
- thunar-standard-view: sets usage-percent via cell_data_func for
computer:// entries using thunar_g_file_get_free_space()
