feat: menu New page (Empty/Database/Kanban) + slash commands / dans l'éditeur

- Topbar bouton New ▾ avec dropdown: Empty page, Database, Kanban board
- page_editor: commandes slash / (/h1, /h2, /list, /todo, /code, /table, /quote...)
- Fonctions JS: createEmptyPage, createDatabase, createBoard
- State showNewPageMenu dans Alpine.js

app/templates/base.html

@@ -226,7 +226,14 @@
         <button class="topbar-btn">🔍</button>
         <button class="topbar-btn share-btn">🔗 Share ▾</button>
         <button class="topbar-btn">⭐</button>
-        <button class="topbar-btn">⋯</button>
+        <button class="topbar-btn" @click="showNewPageMenu = !showNewPageMenu" style="position:relative;">
+          New ▾
+          <div class="dropdown-panel" :class="{ visible: showNewPageMenu }" style="top:100%; right:0; left:auto; min-width:200px;" @click.stop>
+            <div class="dropdown-option" @click="createEmptyPage()"><span class="option-icon">📄</span> Empty page</div>
+            <div class="dropdown-option" @click="createDatabase()"><span class="option-icon">📊</span> Database</div>
+            <div class="dropdown-option" @click="createBoard()"><span class="option-icon">📋</span> Kanban board</div>
+          </div>
+        </button>
       </div>
     </header>
 
@@ -338,6 +345,7 @@
       currentView: 'home',
       contextMenu: { visible: false, x: 0, y: 0, pageId: null, pageName: '' },
       contextActions: {},
+      showNewPageMenu: false,
 
       navigateTo(url) {
         window.location.href = url;
@@ -393,6 +401,19 @@
           .catch(err => { alert('Failed to create sub-page: ' + err.message); });
       },
 
+      createEmptyPage() {
+        this.showNewPageMenu = false;
+        this.newPage('Private');
+      },
+      createDatabase() {
+        this.showNewPageMenu = false;
+        alert('Database creation: use a Gitea repo as a database. Navigate to a project board from the dashboard.');
+      },
+      createBoard() {
+        this.showNewPageMenu = false;
+        window.location.href = '/board/bruno/flowdeck';
+      },
+
       toggleTheme() {
         const html = document.documentElement;
         const current = html.getAttribute('data-theme');