feat(inspect-ui): hierarchy + html panels in run detail

HierarchyPanel renders the captured DOM/AX tree with a filter input.
HtmlPanel renders the per-step HTML in an iframe (sandboxed) with a
toggle to view source. HTML tab only shows when the step actually has
HTML captured.

inspect-ui/src/api.ts

@@ -23,3 +23,7 @@ export function getStep(runId: string, index: number): Promise<Step> {
 export function screenshotUrl(runId: string, name: string): string {
   return `/api/runs/${encodeURIComponent(runId)}/screenshots/${encodeURIComponent(name)}`;
 }
+
+export function htmlUrl(runId: string, name: string): string {
+  return `/api/runs/${encodeURIComponent(runId)}/html/${encodeURIComponent(name)}`;
+}