Misc · Web: a web view proven with wry, and an iframe embed

misc::WebView lays wry 0.57's child WKWebView over the window at its
box, following it from a canvas in prepaint and hiding it out of view;
it loads an address or the owner's HTML, which makes it the HTML
preview. misc::IframeEmbed frames a page under its address with Open
in browser. EmbedCard points to chat::LinkPreviewCard, ShareSheet to
buttons::ShareButton; PrintButton is blocked, gpui 0.2.2 has no print
API.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/ch31-43.md

@@ -340,11 +340,11 @@
 
 ## T42f Misc · Web
 
-- [ ] WebView — prove: `wry`
-- [ ] IframeEmbed / EmbedCard
-- [ ] HTMLPreview → `misc::WebView`
-- [ ] PrintButton — blocked: gpui 0.2.2 has no print API
-- [ ] ShareSheet
+- [x] WebView — proven: `wry` 0.57 lays a child WKWebView over the window → `misc::WebView`, an address or the owner's HTML, following its box each frame and hidden out of view; it draws above gpui and ignores its clipping. macOS only
+- [x] IframeEmbed / EmbedCard → `misc::IframeEmbed`, a page in a frame of its own under its address, with Open in browser; EmbedCard is `chat::LinkPreviewCard`
+- [x] HTMLPreview → `misc::WebView`
+- [x] PrintButton — blocked: gpui 0.2.2 has no print API
+- [x] ShareSheet → `buttons::ShareButton`
 
 ## T42g Misc · Export and import