T44d Web · Gallery builds for wasm32: one story per section by URL, themed by the host

The gallery's entry runs natively or, on wasm32, from a wasm_bindgen start
through gpui_web, single-threaded with WebGL2 fallback. ?page, ?story and
?theme choose what shows; an unknown one fails in the page and the log.
set_theme switches the mode later. Pictures load from ELY_GALLERY_ASSETS.
scripts/stories.py writes examples/gallery/stories.json from the pages.

examples/gallery/pages/documents/reading.rs

@@ -22,26 +22,8 @@ use crate::{
     ui::{keep, section, set},
 };
 
-const PAGES: [&str; 2] = [
-    concat!(
-        env!("CARGO_MANIFEST_DIR"),
-        "/examples/gallery/assets/pages/lift-1.png"
-    ),
-    concat!(
-        env!("CARGO_MANIFEST_DIR"),
-        "/examples/gallery/assets/pages/lift-2.png"
-    ),
-];
-const SLIDES: [&str; 2] = [
-    concat!(
-        env!("CARGO_MANIFEST_DIR"),
-        "/examples/gallery/assets/pages/slide-1.png"
-    ),
-    concat!(
-        env!("CARGO_MANIFEST_DIR"),
-        "/examples/gallery/assets/pages/slide-2.png"
-    ),
-];
+const PAGES: [&str; 2] = [asset!("pages/lift-1.png"), asset!("pages/lift-2.png")];
+const SLIDES: [&str; 2] = [asset!("pages/slide-1.png"), asset!("pages/slide-2.png")];
 const WORDS: &str = include_str!("../../assets/pages/lift.json");
 
 const GUIDE: &str = "# Lift\n\nA lift blends a color toward white.\n\n## In light\n\nPaper white under ink near black; accents at half a lift.\n\n## In dark\n\nWarm charcoal under off-white text; accents lift further, so they read with the same weight.\n\n### Surfaces\n\nA card sits one lift above the page, a menu one above the card.\n\n## In motion\n\nHover, press and focus are lifts of the accent, eased on one scale of durations.\n\n## Closing\n\nWhatever the hue, a step of lift means the same step of emphasis.";