feat: sidebar compact + menu contextuel (clic droit/long press) + boutons Expand/Collapse All

Sidebar workspace:
- Arbre plus compact: padding réduit (4+12*depth au lieu de 8+16),
  gap 4px, min-height 24px, font 13px, chevron 12px
- Boutons d'action (📄📁✏️🗑) remplacés par menu contextuel
  au clic droit (@contextmenu.prevent) et long-press mobile (500ms)
- Menu: New File, New Folder (si dossier), Rename, Delete
- Nom de l'item affiché en bas du menu

Page workspace:
- Boutons ⊞ (Expand All) et ⊟ (Collapse All) dans la toolbar
- expandAll(): parcourt l'arbre, set expanded[id]=true, toggle DOM
- collapseAll(): vide expanded, masque tous les <ul>

app/templates/local_workspace.html

@@ -158,6 +158,8 @@
       📁 <span x-text="breadcrumb.length > 0 ? breadcrumb[breadcrumb.length-1].name : ''"></span>
     </h1>
     <div class="ws-toolbar">
+      <button class="btn-icon" @click="expandAll()" title="Expand all">⊞</button>
+      <button class="btn-icon" @click="collapseAll()" title="Collapse all">⊟</button>
       <button class="btn-icon" @click="openModal('file')" title="New file">📄</button>
       <button class="btn-icon" @click="openModal('folder')" title="New folder">📁</button>
     </div>
@@ -448,6 +450,41 @@ document.addEventListener('alpine:init', function() {
       window.location = '/local-workspace?folder=' + id;
     },
 
+    // ── Expand / Collapse all ──
+    expandAll() {
+      var self = this;
+      this._walkTree(this.tree, function(n) {
+        if (n.is_folder && n.children && n.children.length > 0) {
+          self.expanded[n.id] = true;
+        }
+      });
+      this.expanded = Object.assign({}, this.expanded);
+      // Toggle static HTML for renderChildren
+      this._toggleAllUl(this.$el, true);
+    },
+    collapseAll() {
+      this.expanded = {};
+      this._toggleAllUl(this.$el, false);
+    },
+    _walkTree(nodes, fn) {
+      for (var i=0; i<nodes.length; i++) {
+        fn(nodes[i]);
+        if (nodes[i].children) this._walkTree(nodes[i].children, fn);
+      }
+    },
+    _toggleAllUl(el, show) {
+      var uls = el.querySelectorAll('ul.ws-tree');
+      for (var i=0; i<uls.length; i++) {
+        uls[i].style.display = show ? '' : 'none';
+      }
+      // Also toggle chevrons
+      var chevs = el.querySelectorAll('.ws-chevron');
+      for (var j=0; j<chevs.length; j++) {
+        if (show) chevs[j].classList.add('open');
+        else chevs[j].classList.remove('open');
+      }
+    },
+
     // ── Search / Filter ──
     doFilter() {
       var q = (this.searchQuery || '').toLowerCase().trim();