T25b Generative: queue and results

GenerationQueue shows each job's picture or where it stands, its
prompt and its progress, with Cancel, Retry and Remove as its state
allows; new rows fold in. GenerationGrid lays a run's results out in
their shape: breathing while they come, the picture once done, why one
failed with Retry. VariationPicker shows the chosen variation large
over thumbnails and ways on from it. ABCompareView sets two to four
models' answers side by side, blind until a verdict. ImageCompare
points to data_display::BeforeAfter.

primitives::framed and checked_ratio now serve previews and generative
alike. AGENTS.md records that gpui reads a &str picture as a web
address, and that grid rows overgrow tiles that keep a ratio.

AGENTS.md

@@ -106,6 +106,8 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - gpui's `img` takes its picture's pixel size for any `Auto` side, and its aspect ratio beats percent heights in flow. `Image` pins it absolute at full size, so an `Image` needs a sized box.
 - Badges, tags and avatars live in `data_display`; forms and shell draw theirs from there, and `data_display` imports neither. Avatars take square pictures.
 - `img()` keeps loading state only with an id. Content masks are rectangles, so rounded corners survive only when the image fills its box without cropping.
+- gpui reads a `&str` picture source as a web address. A file goes through `Path` (`documents::source` in the crate, `Path::new` in the gallery).
+- Taffy 0.9's grid rows overgrow tiles that keep a ratio. Tiles in a picture's shape sit in flex rows of `flex_1` cells (`generative::GenerationGrid`).
 - Rise reads green and fall red unless a component's `red_up` swaps them, as markets in East Asia read. `finance::quotes::moves` picks the pair.
 - Charts lay out in `f32` pixels of their own box, tested without gpui, and paint through `charts::paint::at`: a canvas's paint gets window coordinates, and `with_element_offset` works only in prepaint. Their sizes come from `theme.chart()`.
 - A label pinned to a point sits in a zero-size absolute box that centers it with flex (`charts::axes`), so no offset guesses at text size.