feat(ui): implement chat completion views (#2201)

# What does this PR do?
 Implements table and detail views for chat completions

<img width="1548" alt="image"
src="https://github.com/user-attachments/assets/01061b7f-0d47-4b3b-b5ac-2df8f9035ef6"
/>
<img width="1549" alt="image"
src="https://github.com/user-attachments/assets/738d8612-8258-4c2c-858b-bee39030649f"
/>


## Test Plan
npm run test

llama_stack/ui/lib/format-message-content.ts

@@ -0,0 +1,61 @@
+import { ChatMessage, ChatMessageContentPart } from "@/lib/types";
+import { formatToolCallToString } from "@/lib/format-tool-call";
+
+export function extractTextFromContentPart(
+  content: string | ChatMessageContentPart[] | null | undefined,
+): string {
+  if (content === null || content === undefined) {
+    return "";
+  }
+  if (typeof content === "string") {
+    return content;
+  } else if (Array.isArray(content)) {
+    const parts: string[] = [];
+    for (const item of content) {
+      if (
+        item &&
+        typeof item === "object" &&
+        item.type === "text" &&
+        typeof item.text === "string"
+      ) {
+        parts.push(item.text);
+      } else if (
+        item &&
+        typeof item === "object" &&
+        item.type === "image_url"
+      ) {
+        parts.push("[Image]"); // Placeholder for images
+      } else if (typeof item === "string") {
+        // Handle cases where an array might contain plain strings
+        parts.push(item);
+      }
+    }
+    return parts.join(" ");
+  } else {
+    return content;
+  }
+}
+
+export function extractDisplayableText(
+  message: ChatMessage | undefined | null,
+): string {
+  if (!message) {
+    return "";
+  }
+
+  let textPart = extractTextFromContentPart(message.content);
+  let toolCallPart = "";
+
+  if (message.tool_calls && message.tool_calls.length > 0) {
+    // For summary, usually the first tool call is sufficient
+    toolCallPart = formatToolCallToString(message.tool_calls[0]);
+  }
+
+  if (textPart && toolCallPart) {
+    return `${textPart} ${toolCallPart}`;
+  } else if (toolCallPart) {
+    return toolCallPart;
+  } else {
+    return textPart; // textPart will be "" if message.content was initially null/undefined/empty array etc.
+  }
+}