feat(ui): streamline workspace settings and remove sharing

Unify compact workspace controls and panel transitions, move directory actions into the context menu, and remove backlink UI.

Reorganize settings with searchable sections, per-setting resets, shortcut search, and accurate save feedback.

Remove sharing UI, APIs, authentication helpers, and storage code; provide a transactional cleanup script with retirement tests. Reject directories during orphan image cleanup and cover mixed-batch preservation.

internal/watch/watch.go

@@ -170,7 +170,7 @@ func (w *Watcher) scan() (map[string]fileState, error) {
 	return next, nil
 }
 
-// diff 按文件系统身份识别移动，内容相同不代表同一个分享主体。
+// diff 按文件系统身份识别移动，内容相同不代表同一个文件。
 func diff(prev, next map[string]fileState) []events.Event {
 	var evs []events.Event
 	structural := false