v0.55.0

The look-and-feel pass from the 10 October review, a migration wizard that
says how far the copy is, and a PC that stays awake while a job runs.

Added

• The migration wizard shows progress: the Run step has a progress bar,
  files and size copied of the total, folders done, the measured speed, a
  rough time left and the folder being copied, and says plainly when the
  copy is paused, waiting for the NAS or queued. It refreshes by itself.
• The PC stays awake while a background job runs. Windows put a PC to
  sleep in the middle of a long migration; sleep is now held back for as
  long as a job is running (the screen may still turn off).
• Open the report folder on the wizard's Release step.

Changed

• The Release step answers first: "Every source file is accounted for"
  or "N files need attention", then the counts in plain groups, and the
  file list only when something needs attention. A line says why Release is
  off whenever it is.
• One page header and one filled button per page, named after what it
  does; dialogs fill and name their confirming button.
• Settings: Library is split into "Library" and "Recognition &
  autopilot"; darktable moved into Ratings & sidecars and Updates into
  Advanced; labels are centred on their fields; rows that only apply to one
  choice show only with it.
• Tables and lists: more cell padding, no column lines, one tinted
  selected row everywhere, and a line of text instead of a blank box when
  empty.
• Library: a filter that is on is filled and says its value; Ask is a
  mode of the search box; the photo menu is grouped.
• Photo view and Edit: the top bar leaves the details to the Info
  panel; the tool rail shows which tool is on; the Edit panel opens with
  only Light and Color unfolded (your own choice of sections is kept); the
  video trim row is labelled and shows its times.
• Pages: Import is one aligned row ending in Import; Near-duplicates is
  a list with pictures beside its detail; Create tools are a centred card;
  Library status folds its steps when idle; Quarantine, Sensor dust, On
  this day, Map, Stats, Albums and Scene suggestions were tidied.
• Readability: disabled buttons look off, muted text has more contrast
  and nothing is smaller than 12 px.

Fixed

• The Release step opened during the copy listed every file not copied
  yet as "UNACCOUNTED". It now says the copy is still running and checks
  once it has finished.
• A sub-page highlights its parent in the sidebar, and the status bar
  says the catalog snapshot is "saved", not "backed up".