Implement modular report system with 6 report types and composer UI

Refactors the Berichte section from a single hardcoded Jahresbericht into
a modular report-building system. Jahresbericht now uses PDFGenerator for
corporate identity (logo, colors, headers/footers, cover page). 8 reusable
section templates can be freely combined. 6 predefined report templates
(Jahres-, Destinatär-, Grundstücks-, Finanz-, Förder-, Pachtbericht) with
HTML preview and PDF export. New Bericht-Baukasten UI lets users compose
custom reports from individual sections.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/templates/berichte/sektionen/foerderungen.html

@@ -0,0 +1,41 @@
+<!-- Sektion: F&ouml;rderungen (Legacy) -->
+{% if foerderungen %}
+<div class="section">
+  <h2>F&ouml;rderungen {{ jahr }}</h2>
+  <table>
+    <thead>
+      <tr>
+        <th>Beg&uuml;nstigter</th>
+        <th>Kategorie</th>
+        <th>Betrag</th>
+        <th>Status</th>
+        <th>Antragsdatum</th>
+      </tr>
+    </thead>
+    <tbody>
+      {% for f in foerderungen %}
+      <tr>
+        <td>
+          {% if f.destinataer %}{{ f.destinataer.get_full_name }}
+          {% elif f.person %}{{ f.person.get_full_name }}
+          {% else %}&ndash;{% endif %}
+        </td>
+        <td>{{ f.get_kategorie_display }}</td>
+        <td class="amount">&#8364;{{ f.betrag|floatformat:2 }}</td>
+        <td>
+          <span class="status-badge status-{{ f.status }}">{{ f.get_status_display }}</span>
+        </td>
+        <td>{{ f.antragsdatum|date:"d.m.Y" }}</td>
+      </tr>
+      {% endfor %}
+    </tbody>
+    <tfoot>
+      <tr style="font-weight: bold; background: #f0f7f4;">
+        <td colspan="2">Summe</td>
+        <td class="amount">&#8364;{{ total_foerderungen_legacy|floatformat:2 }}</td>
+        <td colspan="2"></td>
+      </tr>
+    </tfoot>
+  </table>
+</div>
+{% endif %}