feat: navigation swipe mobile horizontale

- App.svelte : swipe gauche/droite → même comportement que les touches clavier (navigation entre slides)
- Play.svelte : stopImmediatePropagation sur touchend, blocage du scroll vertical (touchmove)
- Portfolio.svelte : migration du touch vertical (composable) vers horizontal — navigation entre projets, slide voisine aux bords, blocage scroll vertical, debounce 650ms anti-spam

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

src/App.svelte

@@ -79,9 +79,45 @@
       }
     }
     window.addEventListener('keydown', handleKeydown)
+
+    // Swipe gauche/droite → même comportement que les touches clavier
+    const TOUCH_THRESHOLD = 50
+    let touchStartX = 0
+    let touchStartY = 0
+
+    const handleTouchStart = (e) => {
+      touchStartX = e.touches[0].clientX
+      touchStartY = e.touches[0].clientY
+    }
+
+    const handleTouchEnd = (e) => {
+      const deltaX = touchStartX - e.changedTouches[0].clientX
+      const deltaY = touchStartY - e.changedTouches[0].clientY
+      if (Math.abs(deltaX) < TOUCH_THRESHOLD) return
+      if (Math.abs(deltaY) > Math.abs(deltaX)) return
+
+      const activePath = slides.active?.path ?? ''
+      const currentPath = window.location.pathname.replace(/^\/en/, '') || '/'
+      const isSubPage = activePath && currentPath.startsWith(activePath + '/')
+      if (isSubPage) return
+
+      if (deltaX > 0) {
+        const next = slides.all[slides.activeIndex + 1]
+        if (next) slideTo(next.path)
+      } else {
+        const prev = slides.all[slides.activeIndex - 1]
+        if (prev) slideTo(prev.path)
+      }
+    }
+
+    window.addEventListener('touchstart', handleTouchStart, { passive: true })
+    window.addEventListener('touchend', handleTouchEnd, { passive: true })
+
     return () => {
       window.removeEventListener('resize', handleResize)
       window.removeEventListener('keydown', handleKeydown)
+      window.removeEventListener('touchstart', handleTouchStart)
+      window.removeEventListener('touchend', handleTouchEnd)
       clearTimeout(resizeTimer)
     }
   })

src/views/Play.svelte

@@ -101,6 +101,8 @@
 
   function onTouchEnd(e) {
     if (!isActive) return
+    // Toujours intercepter : Play gère lui-même toute la navigation touch
+    e.stopImmediatePropagation()
     const deltaX = touchStartX - e.changedTouches[0].clientX
     if (Math.abs(deltaX) < TOUCH_THRESHOLD) return
 
@@ -137,14 +139,22 @@
     }
   })
 
+  // Bloque le scroll vertical natif (pull-to-refresh, bounce) quand la slide est active
+  function onTouchMove(e) {
+    if (!isActive) return
+    e.preventDefault()
+  }
+
   onMount(() => {
     window.addEventListener('keydown', onKeyDown, { capture: true })
     window.addEventListener('touchstart', onTouchStart, { capture: true, passive: true })
     window.addEventListener('touchend', onTouchEnd, { capture: true, passive: true })
+    window.addEventListener('touchmove', onTouchMove, { passive: false })
     return () => {
       window.removeEventListener('keydown', onKeyDown, { capture: true })
       window.removeEventListener('touchstart', onTouchStart, { capture: true })
       window.removeEventListener('touchend', onTouchEnd, { capture: true })
+      window.removeEventListener('touchmove', onTouchMove)
       clearTimeout(t1)
       clearTimeout(t2)
       clearTimeout(t3)

src/views/Portfolio.svelte

@@ -1,6 +1,7 @@
 <script>
   import { onMount } from 'svelte'
   import { slides } from '@state/slides.svelte'
+  import { slideTo } from '@router'
   import { createScrollNav } from '@composables/useScrollNav.svelte.js'
   import GalleryAnimation from '@components/ui/GalleryAnimation.svelte'
   import ResponsivePicture from '@components/ui/ResponsivePicture.svelte'
@@ -51,15 +52,79 @@
     },
   })
 
+  // --- Touch horizontal (mobile) ---
+  // Même pattern que Play : navigation entre projets, puis slide voisine aux bords.
+  // Le scroll vertical ne fait rien (touchmove bloqué).
+  const TOUCH_THRESHOLD = 50
+  const TOUCH_LOCK_MS = 650
+  let touchStartX = 0
+  let touchStartY = 0
+  let touchLocked = false
+  let touchLockTimer = null
+
+  function onTouchStart(e) {
+    if (!isActive) return
+    touchStartX = e.touches[0].clientX
+    touchStartY = e.touches[0].clientY
+  }
+
+  function onTouchEnd(e) {
+    if (!isActive) return
+    // Toujours intercepter : Portfolio gère lui-même toute la navigation touch
+    e.stopImmediatePropagation()
+    if (touchLocked) return
+    const deltaX = touchStartX - e.changedTouches[0].clientX
+    const deltaY = touchStartY - e.changedTouches[0].clientY
+    if (Math.abs(deltaX) < TOUCH_THRESHOLD || Math.abs(deltaY) > Math.abs(deltaX)) return
+
+    // Verrouillage anti-spam (même durée que le composable useScrollNav)
+    touchLocked = true
+    clearTimeout(touchLockTimer)
+    touchLockTimer = setTimeout(() => { touchLocked = false }, TOUCH_LOCK_MS)
+
+    if (deltaX > 0) {
+      // Swipe gauche → projet suivant, ou slide suivante si fin de liste
+      if (currentIndex < projects.length - 1) {
+        currentIndex++
+        setAnchor(currentIndex)
+      } else {
+        const next = slides.all[slides.activeIndex + 1]
+        if (next) slideTo(next.path)
+      }
+    } else {
+      // Swipe droite → projet précédent, ou slide précédente si début de liste
+      if (currentIndex > 0) {
+        currentIndex--
+        setAnchor(currentIndex)
+      } else {
+        const prev = slides.all[slides.activeIndex - 1]
+        if (prev) slideTo(prev.path)
+      }
+    }
+  }
+
+  // Bloque le scroll vertical natif quand la slide est active
+  function onTouchMove(e) {
+    if (!isActive) return
+    e.preventDefault()
+  }
+
   // --- onMount ---
   onMount(() => {
     sectionEl?.addEventListener('wheel', nav.onWheel, { passive: false })
     window.addEventListener('keydown', nav.onKeyDown)
+    window.addEventListener('touchstart', onTouchStart, { capture: true, passive: true })
+    window.addEventListener('touchend', onTouchEnd, { capture: true, passive: true })
+    window.addEventListener('touchmove', onTouchMove, { passive: false })
 
     return () => {
       sectionEl?.removeEventListener('wheel', nav.onWheel)
       window.removeEventListener('keydown', nav.onKeyDown)
+      window.removeEventListener('touchstart', onTouchStart, { capture: true })
+      window.removeEventListener('touchend', onTouchEnd, { capture: true })
+      window.removeEventListener('touchmove', onTouchMove)
       nav.destroy()
+      clearTimeout(touchLockTimer)
     }
   })
 
@@ -72,6 +137,8 @@
       wasActive = true
     } else if (wasActive) {
       nav.reset()
+      touchLocked = false
+      clearTimeout(touchLockTimer)
       currentIndex = 0
       clearAnchor()
       wasActive = false
@@ -87,8 +154,6 @@
   class="portfolio golden-grid"
   style={backgroundImage ? `--background-image: url('${backgroundImage}')` : ''}
   bind:this={sectionEl}
-  ontouchstart={nav.onTouchStart}
-  ontouchend={nav.onTouchEnd}
   aria-label="Portfolio"
 >
   <!-- Decorative vertical lines -->