feat: Kategorien-Verwaltung auf der Admin-Seite

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

finance/app/templates/admin.html

@@ -32,6 +32,43 @@
   <p id="apply-rules-result"></p>
 </section>
 
+<section class="admin-section">
+  <h2>Kategorien</h2>
+  <p class="muted">Kategorien für Buchungen, Fixposten und Szenario-Modifikatoren.
+     Löschen ist bewusst nicht vorgesehen (Kategorien hängen an Buchungen und Regeln).</p>
+  <table>
+    <thead><tr><th>Name</th><th></th></tr></thead>
+    <tbody>
+      {% for c in categories %}
+      <tr id="cat-row-{{ c.id }}">
+        <td>{{ c.name }}</td>
+        <td><button type="button" onclick="toggleEdit('cat', {{ c.id }}, true)">Bearbeiten</button></td>
+      </tr>
+      <tr id="cat-edit-{{ c.id }}" hidden>
+        <td colspan="2">
+          <form hx-ext="json-form" hx-patch="/api/categories/{{ c.id }}" hx-swap="none"
+                hx-on::after-request="if(event.detail.successful){window.location.reload()}">
+            <label>Name <input type="text" name="name" value="{{ c.name }}" required maxlength="100"></label>
+            <button type="submit">Speichern</button>
+            <button type="button" onclick="toggleEdit('cat', {{ c.id }}, false)">Abbrechen</button>
+          </form>
+        </td>
+      </tr>
+      {% else %}
+      <tr><td colspan="2">Noch keine Kategorien.</td></tr>
+      {% endfor %}
+    </tbody>
+  </table>
+  <fieldset>
+    <legend>Neue Kategorie anlegen</legend>
+    <form hx-ext="json-form" hx-post="/api/categories" hx-swap="none"
+          hx-on::after-request="if(event.detail.successful){window.location.reload()}">
+      <label>Name <input type="text" name="name" required maxlength="100"></label>
+      <button type="submit">Anlegen</button>
+    </form>
+  </fieldset>
+</section>
+
 <script>
   function handleApplyRulesResult(event) {
     var result = document.getElementById('apply-rules-result');