v0.29.0

Changed

• Layout: the 2 px gaps and borders use the shell's Theme tokens (spacingXXS, outlineWidthFocused)
  instead of fixed numbers, with the same size at the default Theme. The popout widths are now
  named properties; they and the desktop picture bounds have no matching Theme token (#123).
• README: a line near the top points to the obsbot4linux project page,
  https://hellwand.github.io/obsbot4linux/, for the tool's install commands (#126).

Fixed

• Desktop widget: on a narrow or short screen (narrower than about 900 logical px, for example
  1280 px at scale 1.5) the picture now shrinks, 16:9 and down to 320 px wide, so that the card
  fits. The shell refused the fixed 640 px size without a message and the side column was cut off.
  The size is asked for again when the screen changes (#114).
• Desktop widget: its options sheet no longer shows the bar and popout toggles, which wrote into
  the desktop instance's own config and had no effect. It shows one line pointing to
  Settings → Plugins instead (#115).
• Watcher: "Control tool not found" goes away as soon as obsbot4linux sends its first state after it is
  back. A Retry (or a popout opened) during the restart backoff no longer leaves the restart timer
  armed, so the next exit waits the backoff again (#116).
• Preview: when another app holds the camera, or Qt finds no video device for it, the picture now
  says "Camera is in use by another app" or "Camera not found" with a Stop preview button instead of
  staying black under "Preview is on". While the preview is off and another app reads the camera,
  the hint says so. The Stop preview button of "Preview unavailable" is hidden while the preview is
  off (#117).
• Desktop widget: on the lock screen it is inert. It starts no watcher, shows no picture and its
  controls are off, and a watcher that was switched off no longer comes back by itself. The widget
  used to be fully live there (#118).