feat(discovery): add FindingDrawer component and restructure i18n keys

- Add FindingDrawer component for displaying finding details when no
  associated issue exists
- Refactor i18n keys for better organization:
  - status.* → session.status.* (session-related)
  - severity.* → findings.severity.* (finding-related)
- Update DiscoveryDetail to show FindingDrawer for orphan findings
- Add severity/priority mapping in discovery-routes for compatibility

ccw/frontend/src/pages/DiscoveryPage.tsx

@@ -7,7 +7,7 @@ import { useIntl } from 'react-intl';
 import { Radar, AlertCircle, Loader2 } from 'lucide-react';
 import { Card } from '@/components/ui/Card';
 import { Badge } from '@/components/ui/Badge';
-import { useIssueDiscovery } from '@/hooks/useIssues';
+import { useIssueDiscovery, useIssues } from '@/hooks/useIssues';
 import { DiscoveryCard } from '@/components/issue/discovery/DiscoveryCard';
 import { DiscoveryDetail } from '@/components/issue/discovery/DiscoveryDetail';
 
@@ -29,6 +29,12 @@ export function DiscoveryPage() {
     isExporting,
   } = useIssueDiscovery({ refetchInterval: 3000 });
 
+  // Fetch issues to find related ones when clicking findings
+  const { issues } = useIssues({
+    // Don't apply filters to get all issues for matching
+    filter: undefined
+  });
+
   if (error) {
     return (
       <div className="space-y-6">
@@ -167,6 +173,7 @@ export function DiscoveryPage() {
               onExport={exportFindings}
               onExportSelected={exportSelectedFindings}
               isExporting={isExporting}
+              issues={issues}
             />
           )}
         </div>