refactor(web): sweep AGENTS.md TypeScript + Mantine rule violations (#1771)

Codebase-wide sweep bringing the web client into strict compliance with the AGENTS.md TypeScript and Mantine/React conventions: ~170 inline 2+-static-prop elements extracted to named .withProps() constants across ~77 files, the AGENTS.md rule wording tightened to match (static-prop boundary + Accordion/Transition/data-*/Box exemptions), a real ScreenStage Box->Flex layout regression fixed (direction: column) with a Storybook regression guard, and an App.tsx double-cast tightened. Closes #1762.

clients/web/src/components/elements/ContentViewer/HtmlFrame.tsx

@@ -25,6 +25,8 @@ export function HtmlFrame({ html }: HtmlFrameProps) {
   );
   const url = useObjectUrl(blob);
   return (
+    // Box+iframe is a native element (not a Mantine primitive), so the
+    // `.withProps()` extraction rule doesn't apply.
     <Box
       component="iframe"
       title="HTML preview"