Add version (0.1.0) and a Settings -> About page

Single source of truth: __version__ in daybook_project/__init__.py, starting
at 0.1.0. Surfaced in two places from that constant:
- Settings -> About page (logo, name, version, description), in the settings
  nav and linked from the gear menu.
- GET /api/capabilities now includes "version", so the deploy agent / tester
  can confirm which version is actually running.

Release flow: bump __version__, commit, `git tag vX.Y.Z`, push tag, deploy.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

artifacts/urls.py

@@ -21,4 +21,5 @@ urlpatterns = [
     path("settings/users/", views.settings_users, name="settings-users"),
     path("settings/demo-data/", views.settings_demo_data, name="settings-demo-data"),
     path("settings/storage/", views.settings_storage, name="settings-storage"),
+    path("settings/about/", views.settings_about, name="settings-about"),
 ]