feat(credits): solde IA unique (option M), packs Stripe et polish billing

Un pot de crédits global (BASIC 100 / PRO 1 000 / BUSINESS 4 000) remplace
les seaux par fonction côté débit. Packs one-shot S/M/L, admin sans seaux
legacy, usage multi-features, hints de coût, anti-flash thème et hydratation
admin. Inclut aussi le pipeline slides renforcé et la page publique polishée.

memento-note/lib/ai/factory.ts

@@ -281,5 +281,40 @@ export function getChatProvider(config?: Record<string, string>): AIProvider {
   return getProviderInstance(route.providerType as ProviderType, cfg, route.modelName, route.embeddingModelName, route.ollamaBaseUrl);
 }
 
+/**
+ * Provider for slide deck generation.
+ * Uses AI_PROVIDER_SLIDES + AI_MODEL_SLIDES when both are set in admin.
+ * If only AI_MODEL_SLIDES is set, reuses the chat provider with that exact model id.
+ * Otherwise falls back to the chat route — never rewrites or invents model names.
+ */
+export function getSlidesProvider(config?: Record<string, string>): AIProvider {
+  const cfg = config || {};
+  const slidesModel = (cfg.AI_MODEL_SLIDES || process.env.AI_MODEL_SLIDES || '').trim();
+  const slidesProvider = (cfg.AI_PROVIDER_SLIDES || process.env.AI_PROVIDER_SLIDES || '').trim();
+  const route = resolveAiRoute('chat', cfg);
+
+  if (slidesModel && slidesProvider) {
+    return getProviderInstance(
+      slidesProvider as ProviderType,
+      cfg,
+      slidesModel,
+      route.embeddingModelName,
+      route.ollamaBaseUrl,
+    );
+  }
+
+  if (slidesModel) {
+    return getProviderInstance(
+      route.providerType as ProviderType,
+      cfg,
+      slidesModel,
+      route.embeddingModelName,
+      route.ollamaBaseUrl,
+    );
+  }
+
+  return getChatProvider(cfg);
+}
+
 // Export for use by admin settings form and deploy scripts
 export { getProviderConfigKeys };