add journaling feature: categories, tags, attachments, calendar, and multi-select emotions

Adds an 8th development stage that lets users keep a free-form journal alongside
habit tracking, reusing the existing Google OAuth/DB/PWA infrastructure instead
of a separate project. Users organize entries into custom categories, filter by
a month calendar with day-detail drill-down, attach photos/videos (served via an
authenticated route, never /static), tag entries, and pick multiple emotions per
entry from a curated 9-option set. Includes a global journal prompt bank for
lightweight guided journaling.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/templates/base.html

@@ -20,6 +20,7 @@
   <script src="/static/js/push-register.js" defer></script>
   <script src="/static/js/vendor/sortable.min.js" defer></script>
   <script src="/static/js/habit-reorder.js" defer></script>
+  <script src="/static/js/journal-category-reorder.js" defer></script>
   <script src="/static/js/vendor/alpine.min.js" defer></script>
   <script src="/static/js/app.js" defer></script>
 </head>
@@ -36,6 +37,7 @@
         <a href="/today" class="{% block nav_today %}{% endblock %}">오늘</a>
         <a href="/habits" class="{% block nav_habits %}{% endblock %}">습관 관리</a>
         <a href="/history" class="{% block nav_history %}{% endblock %}">기록</a>
+        <a href="/journal" class="{% block nav_journal %}{% endblock %}">일기</a>
       </div>
       {% if current_user %}
       <div class="nav-user">
@@ -60,6 +62,10 @@
         <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><rect x="3" y="5" width="18" height="16" rx="2" /><line x1="3" y1="10" x2="21" y2="10" /><line x1="8" y1="3" x2="8" y2="7" /><line x1="16" y1="3" x2="16" y2="7" /></svg>
         <span>기록</span>
       </a>
+      <a href="/journal" class="tab-item {{ self.nav_journal() }}">
+        <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M4 19.5A2.5 2.5 0 0 1 6.5 17H20" /><path d="M6.5 2H20v20H6.5A2.5 2.5 0 0 1 4 19.5v-15A2.5 2.5 0 0 1 6.5 2z" /></svg>
+        <span>일기</span>
+      </a>
     </nav>
     {% endif %}
     {% block content %}{% endblock %}