Renommer lib/ en state/ pour plus de clarté

- Renommage du dossier src/lib/ en src/state/
- Mise à jour de l'alias @lib vers @state dans vite.config.js
- Suppression de l'alias @stores devenu obsolète
- Mise à jour de tous les imports dans les composants et vues

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/layout/Footer.svelte

@@ -1,8 +1,8 @@
 <script>
-  import { siteStore } from '@stores/site'
+  import { site } from '@state/site.svelte'
 
-  $: siteTitle = $siteStore.title || 'World Game'
-  $: currentYear = new Date().getFullYear()
+  const siteTitle = $derived(site.title || 'World Game')
+  const currentYear = $derived(new Date().getFullYear())
 </script>
 
 <footer class="footer">

src/components/layout/Header.svelte

@@ -1,12 +1,12 @@
 <script>
-  import { navigationStore } from '@stores/navigation'
-  import { localeStore } from '@stores/locale'
-  import { pageStore } from '@stores/page'
-  import { navigateTo } from '@lib/router'
+  import { navigation } from '@state/navigation.svelte'
+  import { locale } from '@state/locale.svelte'
+  import { page } from '@state/page.svelte'
+  import { navigateTo } from '@state/router'
 
-  const isMenuOpen = $derived($navigationStore.isMenuOpen)
-  const currentLang = $derived($localeStore.current)
-  const currentPage = $derived($pageStore.template || 'home')
+  const isMenuOpen = $derived(navigation.isMenuOpen)
+  const currentLang = $derived(locale.current)
+  const currentPage = $derived(page.template || 'home')
 
   const translations = {
     expertise: { fr: 'EXPERTISE', en: 'EXPERTISE' },
@@ -25,7 +25,7 @@
   }
 
   function toggleMenu() {
-    navigationStore.toggleMenu()
+    navigation.toggleMenu()
   }
 </script>
 

src/components/ui/Button.svelte

@@ -1,8 +1,8 @@
 <script>
-  export let variant = 'primary' // primary, secondary, outline
-  export let size = 'medium' // small, medium, large
-  export let disabled = false
-  export let href = null
+  let { variant = 'primary' // primary, secondary, outline } = $props()
+  let { size = 'medium' // small, medium, large } = $props()
+  let { disabled = false } = $props()
+  let { href = null } = $props()
 </script>
 
 {#if href}

src/components/ui/VideoBackground.svelte

@@ -1,9 +1,9 @@
 <script>
   import { onMount } from 'svelte'
 
-  export let src
-  export let poster = ''
-  export let overlay = true
+  let { src } = $props()
+  let { poster = '' } = $props()
+  let { overlay = true } = $props()
 
   let videoElement