Progress bars were five raw egui::ProgressBar calls with fixed widths
(240, 260, 380), one hand-drawn bar in the activity stack, and a stock
spinner; text-only waits had no sign of life. progress.rs now has
Progress (a clamped, NaN-safe fraction or a gentle sweep when unknown,
fills the layout's width, announced as a progress indicator with its
percentage and registered by id) and a vector-arc spinner. Button::busy
shows the spinner in the icon's place, keeps the width, ignores clicks
and is announced busy.
Thumbnails still being made draw a themed skeleton colour (a Tokens
field, static) in the grid, the filmstrip and Compare, instead of a
literal grey that was nearly black on the light themes.
Co-Authored-By: Claude <noreply@anthropic.com>
