feat: migrate clients module to patients + add docs

app/epd/_archive/clients_backup_20251122/[id]/plan/page.tsx

@@ -0,0 +1,27 @@
+/**
+ * Behandelplan - Level 2 (Client Dossier)
+ *
+ * SMART doelen tracking met interventies en versioning.
+ */
+
+export default function PlanPage({ params }: { params: Promise<{ id: string }> }) {
+  return (
+    <div>
+      <h1 className="text-2xl font-bold text-slate-900 mb-6">
+        Behandelplan
+      </h1>
+
+      <div className="bg-slate-100 border-2 border-dashed border-slate-300 rounded-lg p-12 text-center">
+        <p className="text-slate-600 text-lg mb-2">
+          SMART Doelen & Interventies
+        </p>
+        <p className="text-slate-500 text-sm">
+          Treatment plan met versioning (v1, v2, concept/gepubliceerd)
+        </p>
+        <p className="text-xs text-slate-400 mt-4">
+          Epic 5 - Placeholder for future content
+        </p>
+      </div>
+    </div>
+  );
+}