portfolio : remove preloadAll, use {#key} for clean project transitions. related to #55

preloadAll caused slow loading by fetching all projects' images at once
(and 404s from srcset strings used as img src). {#key currentIndex}
destroys/recreates DOM on project switch, eliminating stale images.

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

src/views/Portfolio.svelte

@@ -128,28 +128,12 @@
     }
   })
 
-  // --- 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()
@@ -162,9 +146,11 @@
   })
 </script>
 
+{#key currentIndex}
 <div class="portfolio-gallery mobile-only" aria-hidden="true">
   <GalleryAnimation images={currentProject.imagesGallery} backgroundColor={currentProject.galleryBackgroundColor} backgroundImage={currentProject.galleryBackgroundImage} mode={currentProject.galleryAnimationMode} secondsPerImage={currentProject.secondsPerImage} />
 </div>
+{/key}
 
 <section
   class="portfolio golden-grid"
@@ -173,6 +159,7 @@
   aria-label="Portfolio"
 >
   {#if currentProject}
+    {#key currentIndex}
       <!-- Galerie animation (gauche desktop / plein écran mobile) -->
       <div class="portfolio-gallery desktop-only" aria-hidden="true">
         <GalleryAnimation images={currentProject.imagesGallery} backgroundColor={currentProject.galleryBackgroundColor} backgroundImage={currentProject.galleryBackgroundImage} mode={currentProject.galleryAnimationMode} secondsPerImage={currentProject.secondsPerImage} />
@@ -207,6 +194,7 @@
           {/each}
         </div>
       </div>
+    {/key}
   {/if}
 
   <!-- Sidebar navigation -->