feat: add Windows-first deployment flow

backend/main.py

@@ -93,7 +93,7 @@ async def health():
 
 @app.get("/hls/{path:path}")
 async def serve_hls(path: str):
-    hls_root = "/tmp/hls"
+    hls_root = settings.hls_runtime_dir
     fs_path = os.path.join(hls_root, path)
     if os.path.isfile(fs_path):
         return FileResponse(fs_path)
@@ -111,4 +111,4 @@ async def serve_hls(path: str):
                 media_type=resp.headers.get("content-type"),
             )
     except Exception:
-        raise HTTPException(status_code=404)
+        raise HTTPException(status_code=404)