fix: batch priorités — thème, scroll, wizard, agents, slides, charts, packs

Anti-flash dark (color-scheme + applyDocumentTheme), scroll pages publiques,
prompts wizard/slides moins génériques, cron agents rattrapage nextRun null,
slides carnet via notebookId, graphiques à 2 crédits + hint, audit dashboard,
packs Stripe marqués non configurés sans price ID.

memento-note/components/settings/billing-plans.tsx

@@ -576,8 +576,10 @@ export function BillingPlans() {
                 >
                   {packLoading === pack.id ? (
                     <Loader2 className="h-4 w-4 animate-spin mx-auto" />
-                  ) : (
+                  ) : pack.configured ? (
                     t('billing.buyPack')
+                  ) : (
+                    t('billing.packNotConfigured') || 'Config Stripe requise'
                   )}
                 </button>
               </div>