revert: restaure SlidesRenderer (graphes) comme renderer principal

Reverts le changement qui avait cassé les graphes des slides.
data.spec → SlidesRenderer (recharts, graphes OK)
data.html → iframe (fallback si pas de spec)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

memento-note/components/lab/canvas-board.tsx

@@ -218,10 +218,11 @@ function SlidesViewer({ data, name, canvasId }: { data: SlidesPayload; name: str
           </button>
         </div>
       </div>
-      {/* Slides: iframe (new HTML format) preferred over legacy React renderer */}
+      {/* Slides: React renderer (spec) or iframe (HTML fallback) */}
       <div className="flex-1 relative overflow-hidden group">
-        {data.html ? (
-          // New format: standalone animated HTML served via srcDoc
+        {data.spec ? (
+          <SlidesRenderer spec={data.spec} />
+        ) : (
           <>
             {/* Loading overlay — visible until iframe fires onLoad */}
             {!isLoaded && (
@@ -256,10 +257,7 @@ function SlidesViewer({ data, name, canvasId }: { data: SlidesPayload; name: str
               <ChevronRight className="w-5 h-5" />
             </button>
           </>
-        ) : data.spec ? (
-          // Legacy format: old React renderer (recharts)
-          <SlidesRenderer spec={data.spec} />
-        ) : null}
+        )}
       </div>
     </div>
   )