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/views.py

@@ -307,8 +307,11 @@ class CapabilitiesView(APIView):
     def get(self, request):
         if not request.user.is_authenticated and resolve_token_user(request) is None:
             return HttpResponseForbidden("Login or a valid API token is required")
+        from daybook_project import __version__
+
         return Response(
             {
+                "version": __version__,
                 "artifact_kinds": [choice[0] for choice in Artifact.KIND_CHOICES],
                 "filters": ["source", "label", "day", "kind", "q"],
                 "views": ["rendered", "raw"],
@@ -1249,6 +1252,17 @@ def settings_users(request):
     )
 
 
+@login_required
+def settings_about(request):
+    from daybook_project import __version__
+
+    return render(
+        request,
+        "artifacts/settings_about.html",
+        {"active_section": "about", "version": __version__},
+    )
+
+
 @login_required
 def settings_demo_data(request):
     if request.method == "POST":