chore(web): regenerate changelog.generated.ts (Fixed item count 20 -> 21)

Main's Web Frontend check went red after a CHANGELOG entry landed without
the derived file being regenerated. Ran web/scripts/derive-changelog.mjs;
'npm run check' in web/ passes end to end, and vitest
lib/public-copy.test.ts + lib/changelog: 12 passed.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

web/lib/changelog.generated.ts

@@ -63,7 +63,7 @@ export const CHANGELOG: ChangelogRelease[] = [
           "web.run retries a refused page once with a browser user agent, and one site's failure no longer fails the whole call or drops its search results.",
           "Hooks treat bash, Bash and exec_shell as one tool in tool_name conditions, so the documented example fires."
         ],
-        "itemCount": 20
+        "itemCount": 21
       },
       {
         "heading": "Removed",