portfolio : preload all project media on slide activation. related to #55

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/views/Portfolio.svelte

@@ -128,12 +128,28 @@
     }
   })
 
+  // --- Préchargement de tous les médias au premier passage ---
+  let preloaded = false
+
+  function preloadAll() {
+    for (const project of projects) {
+      if (project.mockup) new Image().src = project.mockup
+      if (project.mockupWebp) new Image().src = project.mockupWebp
+      if (project.galleryBackgroundImage) new Image().src = project.galleryBackgroundImage
+      for (const img of (project.imagesGallery ?? [])) {
+        if (img.src) new Image().src = img.src
+        if (img.webp) new Image().src = img.webp
+      }
+    }
+  }
+
   // --- Effect: reset when slide deactivated ---
   // wasActive évite que clearAnchor() s'exécute au montage initial
   // (isActive est false avant l'initialisation des slides)
   let wasActive = false
   $effect(() => {
     if (isActive) {
+      if (!preloaded) { preloaded = true; preloadAll() }
       wasActive = true
     } else if (wasActive) {
       nav.reset()