feat(helpdesk): add Risk Radar dashboard with customer risk scoring

New portfolio view scoring customers 0-100 across five dimensions:
- Open pressure (30%): open + critical ticket count
- Trend (25%): net ticket flow (created - closed) in period
- SLA overdue (20%): tickets exceeding escalation targets
- Resolution time (15%): median hours to close (null = neutral)
- Inactivity (10%): age of oldest open ticket

Card grid with score badges (color-coded high/medium/low), metric
pills, driver bars. Click opens detail dialog with all dimensions
and open ticket list. Clientside search filter.

PBI_LV_Tickets with client-driven paging ($skip/$top, hardcap 5000).
Escalation definitions cached separately (30min TTL). Truncated
banner when data is capped.

New: RiskRadarService, getTicketsForRiskRadar(), 13 PHPUnit tests,
permission helpdesk.risk-radar.view, 2 routes, i18n de+en.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

modules/helpdesk/lib/Module/Helpdesk/Service/DebitorCacheControl.php

@@ -87,6 +87,11 @@ final class DebitorCacheControl
         return 'module.helpdesk.team.v1.workload.' . $tenantScope;
     }
 
+    public static function riskRadarKey(string $tenantScope, int $periodDays): string
+    {
+        return 'module.helpdesk.risk-radar.v1.' . $tenantScope . '.' . $periodDays;
+    }
+
     /**
      * @return array<int, string>
      */