rename: chapitre/projet templates to chapter/project

Standardize French template names to English across blueprints,
content files, PHP templates, Vue components and Pinia stores.

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

src/components/PagedJsWrapper.vue

@@ -40,10 +40,10 @@
         <div v-if="item.text" class="chapeau" v-html="item.text"></div>
       </section>
 
-      <!-- Chapitre -->
+      <!-- Chapter -->
       <section
-        v-else-if="item.template === 'chapitre'"
-        class="chapitre"
+        v-else-if="item.template === 'chapter'"
+        class="chapter"
         :data-page-type="item.template"
       >
         <h3>{{ item.title }}</h3>
@@ -116,7 +116,7 @@ const getBlockComponent = (type) => {
 /* Base print styles for content sections */
 .narrative-cover,
 .geoformat,
-.chapitre,
+.chapter,
 .carte {
   break-before: page;
 }