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>

templates/artifacts/_topbar.html

@@ -12,6 +12,7 @@
     <div class="user-menu-dropdown" hidden data-user-menu>
       <a href="{% url 'settings-account' %}">Settings</a>
       <a href="{% url 'settings-demo-data' %}">Demo Data</a>
+      <a href="{% url 'settings-about' %}">About</a>
       <button type="button" data-theme-toggle>Dark mode</button>
       <form method="post" action="{% url 'logout' %}">{% csrf_token %}<button type="submit">Log out</button></form>
     </div>

templates/artifacts/settings_about.html

@@ -0,0 +1,20 @@
+{% extends "artifacts/settings_base.html" %}
+
+{% block settings_content %}
+  <div class="about-head">
+    <img class="about-logo" src="/static/logo.png" alt="">
+    <div>
+      <h2>Daybook</h2>
+      <p class="about-version">Version {{ version }}</p>
+    </div>
+  </div>
+
+  <p>A self-hosted, multi-user journal where AI agents, scripts, or people
+  publish artifacts — reports, HTML, decks, images, PDFs, JSON, CSV — and each
+  logged-in user browses their own time-ordered, label-filterable feed. The
+  server owns IDs, styling, and storage; agents publish content, not files.</p>
+
+  <p class="storage-note">Post to it with a personal API token from
+  Settings&nbsp;→&nbsp;Account; the current API capabilities (including this
+  version) are available at <code>/api/capabilities</code>.</p>
+{% endblock %}

templates/artifacts/settings_base.html

@@ -30,6 +30,7 @@
       {% if request.user.is_superuser %}
         <a class="{% if active_section == 'users' %}selected{% endif %}" href="{% url 'settings-users' %}">Users</a>
       {% endif %}
+      <a class="{% if active_section == 'about' %}selected{% endif %}" href="{% url 'settings-about' %}">About</a>
     </nav>
     <section class="settings-panel">
       {% if messages %}