Add web management front end (served by the supervisor)

Single-page UI styled after simplex-manager/web/index.html (palette, header,
section-tabs, cards). Talks to the supervisor over REST (control) + WebSocket
(/events live stream):
- Profiles tab: create cli/directory/broadcast, list with status, stop
- Console tab: send raw chat commands to a cli profile, see the response
- Events tab: live event feed from all profiles

server.py serves webui/index.html at /. Validated end to end with curl:
GET / , GET /profiles, start-cli, cmd /user (activeUser), stop.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

supervisor/server.py

@@ -9,15 +9,23 @@ This process sits between the website and the SimpleX binaries; it is the only
 thing that touches the binaries. Run: uvicorn supervisor.server:app
 """
 
-import asyncio
 import contextlib
+from pathlib import Path
 
 from fastapi import FastAPI, WebSocket, WebSocketDisconnect
+from fastapi.responses import FileResponse
 
 from .supervisor import Supervisor
 
 app = FastAPI(title="SimpleX Orchestrate")
 
+WEBUI = Path(__file__).resolve().parent.parent / "webui" / "index.html"
+
+
+@app.get("/")
+async def index() -> FileResponse:
+    return FileResponse(WEBUI)
+
 _browser_clients: set[WebSocket] = set()