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/distribution/server/server.py

@@ -23,6 +23,7 @@ import yaml
 from fastapi import Body, FastAPI, HTTPException, Request
 from fastapi import Path as FastapiPath
 from fastapi.exceptions import RequestValidationError
+from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, StreamingResponse
 from openai import BadRequestError
 from pydantic import BaseModel, ValidationError
@@ -465,6 +466,17 @@ def main(args: argparse.Namespace | None = None):
             window_seconds=window_seconds,
         )
 
+    # --- CORS middleware for local development ---
+    # TODO: move to reverse proxy
+    ui_port = os.environ.get("LLAMA_STACK_UI_PORT", 8322)
+    app.add_middleware(
+        CORSMiddleware,
+        allow_origins=[f"http://localhost:{ui_port}"],
+        allow_credentials=True,
+        allow_methods=["*"],
+        allow_headers=["*"],
+    )
+
     try:
         impls = asyncio.run(construct_stack(config))
     except InvalidProviderError as e: