- Window size/position remembered between sessions via SessionStore
- Step indicator dots now clickable to navigate directly to that step,
with keyboard shortcut hints in tooltips
- File list in add-files dialog shows format and size per image,
header shows total count and total size
- Welcome dialog now saves skill level choice to config
- SessionState extended with window_width, window_height, window_maximized
Preset save/load/list/delete/import/export, config JSON persistence,
session state save/restore, and processing history log with append/clear.
All stored as JSON under ~/.config/pixstrip/.
