feat(helpdesk): replace abstract driver bars with concrete reason texts

Cards now show plain-language reasons instead of abstract progress bars:
'8 open, 3 critical', '↑4 more than resolved', '2 SLA breaches',
'Oldest ticket 12d'. Instantly understandable without knowing the
scoring formula. Driver bars remain in the detail dialog for the
full dimension breakdown.

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

modules/helpdesk/i18n/default_de.json

@@ -323,5 +323,8 @@
   "open": "offen",
   "overdue": "überfällig",
   "net": "netto",
-  "Search customers...": "Kunden suchen..."
+  "Search customers...": "Kunden suchen...",
+  "more than resolved": "mehr als gelöst",
+  "SLA breaches": "SLA-Verletzungen",
+  "Oldest ticket": "Ältestes Ticket"
 }