✨(backend) add async_mode flag

the command must be killable.
this adds a async_mode flag to preserve async
feature and allow running sync.

Signed-off-by: charles <charles.englebert@protonmail.com>

src/backend/core/admin.py

@@ -248,6 +248,7 @@ def run_indexing_view(request: HttpRequest):
                 upper_time_bound=convert_to_isoformat(
                     request.POST.get("upper_time_bound")
                 ),
+                async_mode=True,
             )
             messages.success(request, _("Indexing triggered!"))
         else: