feat(api): serve the API through the gunicorn ASGI worker

Run gunicorn with the native asgi worker against config.asgi so SSE
streams are parked on the event loop instead of holding a sync worker
per open connection; sync CRUD views keep running in the thread-sensitive
executor. Disable preload under DEBUG so dev reload picks up edited code,
and point the dev and prod entrypoints at the ASGI application.

api/docker-entrypoint.sh

@@ -21,13 +21,19 @@ apply_fixtures() {
 }
 
 start_dev_server() {
-  echo "Starting the development server..."
-  exec uv run python manage.py runserver 0.0.0.0:"${DJANGO_PORT:-8080}"
+  echo "Starting the development server (Gunicorn ASGI, debug + reload)..."
+  # Same server/worker as prod (config.asgi via the native `asgi` worker), so
+  # SSE streams run on the event loop exactly as they do in production. DEBUG is
+  # on so guniconf's `reload = DEBUG` hot-reloads edited code (and flips
+  # `preload_app` off so reload actually takes).
+  export DJANGO_DEBUG="${DJANGO_DEBUG:-True}"
+  export DJANGO_BIND_ADDRESS="${DJANGO_BIND_ADDRESS:-0.0.0.0}"
+  exec uv run gunicorn -c config/guniconf.py config.asgi:application
 }
 
 start_prod_server() {
   echo "Starting the Gunicorn server..."
-  exec uv run gunicorn -c config/guniconf.py config.wsgi:application
+  exec uv run gunicorn -c config/guniconf.py config.asgi:application
 }
 
 resolve_worker_hostname() {

api/src/backend/config/guniconf.py

@@ -25,6 +25,15 @@ bind = f"{BIND_ADDRESS}:{PORT}"
 workers = env.int("DJANGO_WORKERS", default=multiprocessing.cpu_count() * 2 + 1)
 reload = DEBUG
 
+# Native ASGI worker (gunicorn 24+). Required so SSE endpoints can keep the
+# event loop alive while waiting for events.
+worker_class = env("DJANGO_WORKER_CLASS", default="asgi")
+
+# Preload the application before forking workers in production: the app is
+# imported once in the master and workers fork from it. In development, disable
+# preload so the server restarts on code changes.
+preload_app = not DEBUG
+
 # Logging
 logconfig_dict = DJANGO_LOGGERS
 gunicorn_logger = logging.getLogger(BackendLogger.GUNICORN)