feat(helpdesk): add dashboards, communication feed, settings UI and fix routing

Add support/sales/controlling dashboards with KPIs, trend charts and
risk indicators. Add debitor communication timeline, contact filters,
system recommendations engine, and configurable controlling risk rules.

Rename search→index to fix query-string preservation on back navigation.
Remove fake escalation rate metric, add KPI info tooltips, and switch
trend chart colors to red (created) / green (closed) for clarity.

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

modules/helpdesk/web/js/helpdesk-communication.js

@@ -1,3 +1,5 @@
+import { renderEmptyState } from './helpdesk-empty-state.js';
+
 function esc(str) {
   const d = document.createElement('div');
   d.textContent = String(str ?? '');
@@ -72,9 +74,12 @@ export function renderCommunicationFeed(entries, options = {}) {
 
   const list = Array.isArray(entries) ? entries : [];
   if (list.length === 0) {
-    return `<div class="app-empty-state app-empty-state-compact">
-      <p class="app-empty-state-message">${esc(t(emptyMessage))}</p>
-    </div>`;
+    return renderEmptyState({
+      message: t(emptyMessage),
+      size: 'compact',
+      align: 'center',
+      icon: false,
+    });
   }
 
   let html = '<ol class="helpdesk-comm-feed" role="list">';