feat(ui): add views for Responses (#2293)

# What does this PR do?
* Add responses list and detail views
* Refactored components to be shared as much as possible between chat
completions and responses

## Test Plan
<img width="2014" alt="image"
src="https://github.com/user-attachments/assets/6dee12ea-8876-4351-a6eb-2338058466ef"
/>
<img width="2021" alt="image"
src="https://github.com/user-attachments/assets/6c7c71b8-25b7-4199-9c57-6960be5580c8"
/>

added tests

llama_stack/ui/components/responses/items/item-renderer.tsx

@@ -0,0 +1,60 @@
+import {
+  isMessageItem,
+  isFunctionCallItem,
+  isWebSearchCallItem,
+  AnyResponseItem,
+} from "../utils/item-types";
+import { MessageItemComponent } from "./message-item";
+import { FunctionCallItemComponent } from "./function-call-item";
+import { WebSearchItemComponent } from "./web-search-item";
+import { GenericItemComponent } from "./generic-item";
+
+interface ItemRendererProps {
+  item: AnyResponseItem;
+  index: number;
+  keyPrefix: string;
+  defaultRole?: string;
+}
+
+export function ItemRenderer({
+  item,
+  index,
+  keyPrefix,
+  defaultRole = "unknown",
+}: ItemRendererProps) {
+  if (isMessageItem(item)) {
+    return (
+      <MessageItemComponent
+        item={item}
+        index={index}
+        keyPrefix={keyPrefix}
+        defaultRole={defaultRole}
+      />
+    );
+  }
+
+  if (isFunctionCallItem(item)) {
+    return (
+      <FunctionCallItemComponent
+        item={item}
+        index={index}
+        keyPrefix={keyPrefix}
+      />
+    );
+  }
+
+  if (isWebSearchCallItem(item)) {
+    return (
+      <WebSearchItemComponent item={item} index={index} keyPrefix={keyPrefix} />
+    );
+  }
+
+  // Fallback to generic item for unknown types
+  return (
+    <GenericItemComponent
+      item={item as any}
+      index={index}
+      keyPrefix={keyPrefix}
+    />
+  );
+}