Adds a Copy action (puts an item on the clipboard and moves it to the top
without pasting). Fixes the UI freeze when searching large lists (database
moved off the UI thread) and the Windows image-paste name collision in
Explorer/Desktop (now offers CF_HDROP with the file's unique name).
Hardening: error handling, stale temp-file cleanup, XDG autostart, MSIX
reveal, and native thumbnail-provider dedup.
Severity: recommended
Min-Supported: 2.3.0
Full Changelog: v2.5.0...v2.6.0