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/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 %}