Adopt component macro 0.5.0: required props, Into setters, composed apply

[JedimEmO]

Summary

Adopts futures-signals-component-macro 0.5.0 across dwui and the webpage. Depends on that PR — see the merge checklist below.

Required props, enforced at compile time

card.content, heading.content, and virtual_scroll.render_item are now #[required]. Omitting them was previously a silent empty render (or a placeholder div for the virtual scroller); it is now a targeted compile error:

error[E0277]: missing required props for component `card`
   | required props: `content` — set each with `.content(...)`

The enforcement immediately caught two real bugs: card! call sites in components_page.rs and example_small.rs that injected children through .apply() and never set content — both now pass real content nodes.

#[into] ergonomics

All Option<Dom>, String, and optional-scalar props across 26 components take impl Into<T> now. Call-site cleanup: 50 .content(Some(...)) → .content(...), 86 literal .to_string() args dropped, and the four .content(html!(...).into()) sites that would have become ambiguous pass the Dom directly.

Spotlight bug fixed by composed apply

section_card calls .apply(crate::fx::spotlight) followed by a second .apply(...); under 0.4 the second call silently discarded the first, so the gallery spotlight effect was dead code. With composing apply it works again — verified in headless Chrome: all 24 section cards carry the --sx/--sy spotlight vars on hover, layout is unchanged, zero console errors, and the restructured modal example opens with its focus trap intact.

Render-fn apply handling is untouched (the prop keeps its Option<Box<dyn FnOnce>> type) — dwui compiled with zero source edits against the new macro before any of this adoption, which was verified explicitly.

Test plan

• cargo check --workspace --all-targets, cargo test (native)
• wasm-pack test --headless --firefox crates/dwui — 51 component + 19 styling browser tests green
• cargo clippy — zero new warnings vs baseline; cargo fmt --check at exact parity with pre-existing state
• trunk build + headless-Chrome visual verification of the components page (spotlight vars, layout, modal open/close)
• cargo doc -p dwui — generated macro doc tables now mark [required] and impl Into<T> setters

Merge checklist

• Land Add #[required] typestate props, #[into] setters, and composing apply (0.5.0) futures-signals-component-macro#9, tag v0.5.0, publish to crates.io
• Drop the temporary [patch.crates-io] path override from the root Cargo.toml (CI cannot resolve the local path; this PR stays draft until then)

🤖 Generated with Claude Code