feat: Szenarien-Seite mit zwei Formularen, Zeitraum-Spalte und wiederkehrenden Szenario-Zahlungen (A14-T4)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

finance/app/templates/base.html

@@ -8,6 +8,7 @@
   <script src="/static/htmx.min.js?v={{ app_version }}"></script>
   <script src="/static/sort.js?v={{ app_version }}"></script>
   <script src="/static/doppelzaehlung.js?v={{ app_version }}"></script>
+  <script src="/static/szenarien.js?v={{ app_version }}"></script>
 </head>
 <body>
   <nav>
@@ -100,6 +101,7 @@
     }
 
     if (window.FBDoppel) { window.FBDoppel.init(document); }
+    if (window.FBSzenario) { window.FBSzenario.init(document); }
   </script>
   <footer class="version">Finanzberatungs-Tool v{{ app_version }}</footer>
 </body>