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.

scripts/check.sh

@@ -4,6 +4,7 @@ set -eu
 cargo fmt --check
 cargo clippy --all-targets --features test-support -- -D warnings
 cargo test --lib --features test-support --quiet
+python3 scripts/stories.py --check
 fail=0
 files=$(git ls-files -co --exclude-standard '*.rs')
 multi=$(awk 'FNR==1{prev=0} /^[[:space:]]*\/\// {if(prev) print FILENAME":"FNR; prev=1; next} {prev=0}' $files)
@@ -17,6 +18,6 @@ raw=$(awk '/#\[cfg\(test\)\]/{nextfile} /(^|[^.[:alnum:]_])px\(/{print FILENAME"
 [ -z "$raw" ] || { echo "raw px in components:"; echo "$raw"; fail=1; }
 deferred=$(grep -rn 'deferred(' src --include='*.rs' | grep -v '^src/primitives/layer.rs' || true)
 [ -z "$deferred" ] || { echo "gpui deferred outside primitives::raise:"; echo "$deferred"; fail=1; }
-instant=$(grep -rnE '(^|[^_[:alnum:]])time::(Instant|\{[^}]*Instant)' src || true)
+instant=$(grep -rnE '(^|[^_[:alnum:]])time::(Instant|\{[^}]*Instant)' src examples || true)
 [ -z "$instant" ] || { echo "std Instant panics in the browser, use web_time::Instant:"; echo "$instant"; fail=1; }
 exit $fail