fix: import type + lazy singleton pour dagre et pptxgenjs (Turbopack build)

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

memento-note/lib/ai/tools/pptx.tool.ts

@@ -1,6 +1,16 @@
 'use server'
 
-import PptxGenJS from 'pptxgenjs'
+// import type is erased at build time — Turbopack won't try to resolve the module
+import type PptxGenJSModule from 'pptxgenjs'
+// Lazy singleton — actual module loaded at runtime only
+let _PptxGenJS: (new () => PptxGenJSModule) | null = null
+async function getPptxGenClass(): Promise<new () => PptxGenJSModule> {
+  if (!_PptxGenJS) {
+    const mod = await import('pptxgenjs')
+    _PptxGenJS = (mod.default ?? mod) as unknown as new () => PptxGenJSModule
+  }
+  return _PptxGenJS
+}
 import { tool } from 'ai'
 import { z } from 'zod'
 import { toolRegistry } from './registry'
@@ -960,10 +970,11 @@ function addClosingSlide(pres: PptxGenJS, spec: PresentationSpec, t: Theme, styl
   return s
 }
 
-function buildPresentation(spec: PresentationSpec): PptxGenJS {
+async function buildPresentation(spec: PresentationSpec): Promise<PptxGenJSModule> {
   const { theme } = resolveTheme(spec)
   const style = STYLES[spec.style || 'soft'] || STYLES.soft!
 
+  const PptxGenJS = await getPptxGenClass()
   const pres = new PptxGenJS()
   pres.title = spec.title
   pres.author = 'Momento'
@@ -1131,7 +1142,7 @@ RULES:
             }
           }
 
-          const pptx = buildPresentation(spec)
+          const pptx = await buildPresentation(spec)
           const base64 = await pptx.write({ outputType: 'base64' }) as string
 
           const canvas = await prisma.canvas.create({