(feature) add Django setup flow for initial pobsync configuration

Add staff-only UI routes for creating/editing the default GlobalConfig
and creating the first HostConfig from the dashboard.

Improve the empty dashboard state so a fresh database guides the user
towards the next useful setup action instead of only showing empty tables.

Cover the setup flow with view tests for empty state prompts, global
config creation, and host creation.

src/pobsync_server/urls.py

@@ -8,6 +8,8 @@ from pobsync_backend import api, views
 
 urlpatterns = [
     path("", views.dashboard, name="dashboard"),
+    path("config/global/", views.edit_global_config, name="edit_global_config"),
+    path("hosts/new/", views.create_host_config, name="create_host_config"),
     path("hosts/<str:host>/", views.host_detail, name="host_detail"),
     path("hosts/<str:host>/config/", views.edit_host_config, name="edit_host_config"),
     path("hosts/<str:host>/discover-snapshots/", views.discover_host_snapshots, name="discover_host_snapshots"),