web UI added and refactoring done

python_app/webui/app.py

@@ -0,0 +1,43 @@
+"""FastAPI application factory for the embedded radar web UI.
+
+The controller (the Qt bridge that forwards to the AppWindow) is created and
+owned by the host process and injected here. The app's only owned resource is the
+:class:`RingBroadcaster` polling task, created and torn down by the lifespan. The
+static single-page frontend is mounted at ``/`` and the JSON/WS API under
+``/api`` and ``/ws``.
+"""
+
+from __future__ import annotations
+
+from contextlib import asynccontextmanager
+from pathlib import Path
+
+from fastapi import FastAPI
+from fastapi.staticfiles import StaticFiles
+
+from python_app.webui.controller import WebController
+from python_app.webui.routes import router
+from python_app.webui.streaming import RingBroadcaster
+
+_STATIC_DIR = Path(__file__).resolve().parent / "static"
+
+
+def create_app(controller: WebController) -> FastAPI:
+    """Build the FastAPI app that serves and streams for ``controller``."""
+
+    @asynccontextmanager
+    async def lifespan(app: FastAPI):
+        broadcaster = RingBroadcaster(controller)
+        app.state.controller = controller
+        app.state.broadcaster = broadcaster
+        broadcaster.start()
+        try:
+            yield
+        finally:
+            await broadcaster.stop()
+
+    app = FastAPI(title="Radar Web UI", lifespan=lifespan)
+    app.include_router(router)
+    # Mount the SPA last so the API routes above always take precedence.
+    app.mount("/", StaticFiles(directory=_STATIC_DIR, html=True), name="static")
+    return app