fix: Convert all remaining Date objects to ISO strings and fix client type in factures/nouvelle

app/(main)/factures/relances/[id]/page.tsx

@@ -548,7 +548,7 @@ const FactureRelancePage = () => {
                             <Calendar
                                 id="dateEnvoi"
                                 value={nouvelleRelance.dateEnvoi}
-                                onChange={(e) => setNouvelleRelance(prev => ({ ...prev, dateEnvoi: e.value || new Date() }))}
+                                onChange={(e) => setNouvelleRelance(prev => ({ ...prev, dateEnvoi: e.value?.toISOString() || new Date().toISOString() }))}
                                 className="w-full"
                                 dateFormat="dd/mm/yy"
                                 showTime