Feat: pages Article + navigation blog/article interne

- Router: findSlideIndex() avec fallback parent path
  (/blog/slug → /blog) pour sub-pages
- article.json.php: réécriture — date, intro, cover, body (blocks→HTML),
  related articles (fallback siblings si vide)
- Article.svelte: sous-composant — topbar date+retour, titre Terminal,
  intro, cover, body rich text (styles :global pour blocks Kirby),
  related articles grid, responsive
- Blog.svelte: gère deux modes (liste + article) —
  intercepte les clics article via stopPropagation (avant le router),
  fetch article data, pushState pour URL, popstate pour back/forward,
  direct navigation /blog/slug sur mount

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/router/index.js

@@ -8,16 +8,39 @@ function normalizePath(path) {
   return path === "/" ? "/home" : path;
 }
 
+/**
+ * Trouve l'index de la slide correspondant au path.
+ * Si le path exact n'existe pas, essaie le chemin parent
+ * (ex: /blog/article-slug → /blog).
+ */
+function findSlideIndex(path) {
+  let idx = slides.getIndexByPath(path);
+  if (idx !== -1) return idx;
+  const parentPath = path.replace(/\/[^/]+$/, "");
+  if (parentPath) return slides.getIndexByPath(parentPath);
+  return -1;
+}
+
 async function loadSlide(path) {
-  const idx = slides.getIndexByPath(path);
+  let slidePath = path;
+  let idx = slides.getIndexByPath(slidePath);
+
+  // Sub-page: resolve to parent slide (ex: /blog/slug → /blog)
+  if (idx === -1) {
+    const parentPath = path.replace(/\/[^/]+$/, "");
+    idx = slides.getIndexByPath(parentPath);
+    if (idx !== -1) slidePath = parentPath;
+  }
+
   if (idx !== -1) {
     const slide = slides.all[idx];
     if (slide.loaded || slide.loading) return;
-    slides.setLoading(path, true);
+    slides.setLoading(slidePath, true);
   }
 
   try {
-    const response = await fetch(`${path}.json`);
+    // Fetch the actual slide path (parent), not the sub-page
+    const response = await fetch(`${slidePath}.json`);
     if (!response.ok) throw new Error(`HTTP ${response.status}`);
     const data = await response.json();
 
@@ -28,10 +51,10 @@ async function loadSlide(path) {
       siteInitialized = true;
     }
 
-    slides.setData(path, data);
+    slides.setData(slidePath, data);
   } catch (error) {
-    console.error(`[router] Failed to load slide ${path}:`, error);
-    slides.setLoading(path, false);
+    console.error(`[router] Failed to load slide ${slidePath}:`, error);
+    slides.setLoading(slidePath, false);
   }
 }
 
@@ -48,15 +71,17 @@ export function slideTo(path, { skipHistory = false } = {}) {
     history.pushState({}, "", path === "/home" ? "/" : path);
   }
 
-  const idx = slides.getIndexByPath(path);
+  const idx = findSlideIndex(path);
+  const slidePath = idx !== -1 ? slides.all[idx].path : path;
+
   if (idx !== -1 && slides.all[idx].title) {
     document.title = `${slides.all[idx].title} — World Game`;
   }
 
-  slides.slideTo(path);
+  slides.slideTo(slidePath);
 
   if (idx !== -1 && !slides.all[idx].loaded) {
-    loadSlide(path);
+    loadSlide(slidePath);
   }
 }
 
@@ -65,12 +90,14 @@ export async function initRouter() {
 
   await loadSlide(initialPath);
 
-  const idx = slides.getIndexByPath(initialPath);
+  const idx = findSlideIndex(initialPath);
   if (idx !== -1) {
     slides.setActiveIndex(idx);
   }
 
-  loadAllSlidesInBackground(initialPath);
+  loadAllSlidesInBackground(
+    idx !== -1 ? slides.all[idx].path : initialPath
+  );
 
   window.addEventListener("popstate", () => {
     const path = normalizePath(window.location.pathname);