fix: apply the review items for #730 at merge

Set --rv-content-max: none on the File Viewer's rendered document, so
ASCII-diagram blocks (capped by that variable with a 720px fallback the
Response Viewer sets) follow the window like the rest of the document,
and pin it with a third assertion.

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

src/web/public/styles.css

@@ -12549,12 +12549,16 @@ html:is([data-skin="paper-gray"], [data-skin="solarized-light"], [data-skin="cat
    No width cap. The window is whatever the user drags or expands it to, so the
    document must reflow to fill it; the fixed 960px reading column this rule
    shipped before the resize grip existed stops reflow once the window is wider
-   than the cap. Pinned by test/file-preview-window.test.ts. */
+   than the cap. --rv-content-max: none lets ASCII-diagram blocks
+   (.rv-text .rv-diagram-wrap, capped by that variable with a 720px fallback
+   meant for the Response Viewer) follow the rest of the document too. Pinned by
+   test/file-preview-window.test.ts. */
 
 .file-preview-body > .file-preview-md {
   padding: 1rem 1.25rem 2rem;
   font-size: 15px;
   line-height: 1.55;
+  --rv-content-max: none;
 }
 
 /* Relative links in the document are rebased onto a.rv-path so the Response