fix: 'Root' retiré du path + menu dropdown clippé par overflow sidebar

- folderStack: supprimé {id:0, name:'Root'} dans init() et navigateToRoot()
  → breadcrumb n'affiche plus 'Workspace / Root' mais juste 'Workspace / dossier'
- Sidebar: overflow-y:auto déplacé de .sidebar vers .sidebar-scroll (flex child)
  → le header et son dropdown ne sont PLUS clippés par overflow
  → position: absolute + top:100% fonctionne maintenant sur le dropdown
- .sidebar-scroll wrapper autour du contenu scrollable (nav row → footer)

app/templates/local_workspace.html

@@ -907,7 +907,7 @@ document.addEventListener('alpine:init', function() {
     },
 
     async navigateToRoot() {
-      this.folderStack = [{id: 0, name: 'Root'}];
+      this.folderStack = [];
       this.navIndex = 0;
       this._saveExpandedState();
       await this._loadFolder(0);
@@ -980,15 +980,7 @@ document.addEventListener('alpine:init', function() {
         this.loaded = true;
         // Initialize folder stack from breadcrumb
         this.folderStack = (this.breadcrumb || []).map(function(b) { return {id: b.id, name: b.name}; });
-        if (this.currentFolder && this.currentFolder > 0 && this.folderStack.length === 0) {
-          this.folderStack = [{id: 0, name: 'Root'}];
-          // Add current folder name from tree if present
-          if (this.tree.length > 0) {
-            // The current folder's children are in breadcrumb, parent is the last
-          }
-        }
         this.navIndex = this.folderStack.length > 0 ? this.folderStack.length - 1 : 0;
-        if (this.folderStack.length === 0) this.folderStack = [{id: 0, name: 'Root'}];
         // Expose globally for renderChildren onclick handlers
         window._wsData = this;
         // Listen for online/offline