fix(i18n): Beschreibung-generieren-Button + Fehler-Toasts uebersetzbar

- Button-Span enhance-btn-text bekommt data-i18n.
- app.js: Loading-State Wird generiert... / Generating... per T().
- Vier Fehler-Toasts (Default, 503, 429, 504) per T() lokalisiert.
- Neue Keys enhance.* in de.json + en.json.
- Cache-Buster app.js auf v=20260513c gebumpt.

src/static/dashboard.html

@@ -341,7 +341,7 @@
                         <div class="description-label-row">
                             <label for="inc-description">Beschreibung / Kontext <span class="info-icon tooltip-below" id="description-info-icon" data-tooltip="Beschreibe den Vorfall möglichst genau: Was ist passiert? Wo? Wer ist beteiligt? Je präziser, desto bessere Ergebnisse."><svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><path d="M12 16v-4"/><path d="M12 8h.01"/></svg></span></label>
                             <button type="button" class="btn btn-secondary btn-small" id="btn-enhance-description" onclick="App.generateDescription()" disabled>
-                                <span id="enhance-btn-text">Beschreibung generieren</span>
+                                <span id="enhance-btn-text" data-i18n="modal.new_incident.enhance">Beschreibung generieren</span>
                                 <span id="enhance-spinner" class="spinner-inline" style="display:none;"></span>
                             </button>
                         </div>
@@ -729,7 +729,7 @@
     <script src="/static/js/components.js?v=20260513a"></script>
     <script src="/static/js/layout.js?v=20260316b"></script>
     <script src="/static/js/pipeline.js?v=20260501i"></script>
-    <script src="/static/js/app.js?v=20260513b"></script>
+    <script src="/static/js/app.js?v=20260513c"></script>
     <script src="/static/js/cluster-data.js?v=20260322f"></script>
     <script src="/static/js/tutorial.js?v=20260316z"></script>
     <script src="/static/js/chat.js?v=20260422a"></script>