Add Recharts bar charts to Today dashboard summary.

Extend the Today summary API with treatment mix and workflow task breakdowns, and render permission-aware chart cards on the Today page using Recharts.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/messages/nl.json

@@ -207,7 +207,12 @@
     "widgetImportantTasks": "Belangrijke taken",
     "widgetPendingConnections": "Openstaande koppelingsverzoeken",
     "widgetSeats": "Zitplaatsgebruik",
-    "widgetPendingStaffInvites": "Openstaande medewerkersuitnodigingen"
+    "widgetPendingStaffInvites": "Openstaande medewerkersuitnodigingen",
+    "chartTreatmentMixTitle": "Behandelingsmix",
+    "chartTreatmentMixSubtitle": "Afgelopen 7 dagen",
+    "chartTasksByStepTitle": "Taken per workflowstap",
+    "chartTasksByStepSubtitle": "Nu in uitvoering",
+    "chartEmpty": "Nog geen gegevens voor deze periode."
   },
   "staff": {
     "redirecting": "Bezig met doorsturen...",