Helix Boot v0.6.5

A round of fixes from a review of everything added since 0.5.3. Two of them could lose data in unusual situations, so updating is recommended:

• an update from another PC that failed half-way could lose the stick's own icons and splash;
• on a stick last written by 0.6.1 or older, a tool could be removed as an "old version" of another whose file name differed only in a number.

Also: a refresh that changes nothing now writes nothing to the stick's theme, and Lazarus PE and Super GRUB2 Disk have icons in the default set.

Fixed

From a review of everything since 0.5.3:

• A stick's own icons and splash could be lost for good if an update from
  another PC failed half-way: they were moved aside first. They now stay in
  place.
• On a stick last written by 0.6.1 or older, a tool could be taken for an old
  version of another whose file name differed only in a number
  (windows10.iso, windows11.iso) and be removed. Only a download named after
  its version is matched that way now.
• A stick given a name of your own (stick_label), or renamed, was refused by
  refresh.sh and Update if its first fill had been cut short. It is known by
  Ventoy's own partition beside it.
• In the Windows app, Apply in the Look window could run while an update
  was copying. The Look window now holds the app while it is open.
• A dry run, and the app's update summary, listed an image that only moves
  folder as one to be removed.
• A look.json on the stick with a value this version doesn't know crashed
  theme.sh and left the Look… button doing nothing.
• In the Look window, a picture chosen but not sent was treated as already on
  the stick after Apply.
• A boot menu or theme file that couldn't be written on Windows was reported
  as "in use" and the update still ended as a success; only the running app's
  own file is let through now.
• refresh.sh <folder> stopped with an error after a good sync when the folder
  wasn't on a plain partition.

Changed

• A refresh that changes nothing writes nothing to the stick's theme: the
  theme on the stick is updated in place, and the boot menu is only rebuilt
  when what it is built from changed.

Added

• Icons in the default set for the two entries that still had their classic
  ones: Lazarus PE (the phoenix on a glossy badge, drawn by
  docs/artwork/helix-icons/make-lazarus-pe.py) and Super GRUB2 Disk.