fix(ui): strict-TS cast in peers per-onion grouping

vue-tsc rejected the double cast; vitest strips types so it slipped
through. Narrow once into a local instead.

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

neode-ui/src/services/contextBroker.ts

@@ -326,7 +326,8 @@ export class ContextBroker {
       if (s.scope === 'peers') {
         const byOnion = new Map<string, ArchyContentItem[]>()
         for (const it of items) {
-          const onion = typeof (it as { peer?: unknown }).peer === 'string' ? (it as { peer: string }).peer : ''
+          const peer: unknown = (it as { peer?: unknown }).peer
+          const onion = typeof peer === 'string' ? peer : ''
           if (!onion) continue
           byOnion.set(onion, [...(byOnion.get(onion) ?? []), it])
         }