style(workspace): move sidebar toggle to the left as icon-only button

frontend/src/features/workspace/WorkspaceView.tsx

@@ -1026,8 +1026,28 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     <div className="w-full space-y-3">
       {/* Top Header: Workspace Tabs & Actions */}
       <div className="flex flex-wrap items-center justify-between gap-2 border-b border-border pb-2">
-        {/* Workspace selector tabs */}
+        {/* Workspace selector tabs & left sidebar toggle */}
         <div className="flex flex-wrap items-center gap-1">
+          {subView === 'editor' && (
+            <button
+              type="button"
+              onClick={toggleSidebar}
+              className={`hidden sm:inline-flex h-8 w-8 items-center justify-center rounded-btn border transition-colors cursor-pointer ${
+                isSidebarCollapsed
+                  ? 'bg-panel border-accent text-accent'
+                  : 'bg-canvas border-border text-muted hover:text-main'
+              }`}
+              title={isSidebarCollapsed ? 'Ordnerleiste einblenden' : 'Ordnerleiste einklappen'}
+              aria-label={isSidebarCollapsed ? 'Ordnerleiste einblenden' : 'Ordnerleiste einklappen'}
+            >
+              {isSidebarCollapsed ? (
+                <PanelLeftOpen className="w-4 h-4" />
+              ) : (
+                <PanelLeftClose className="w-4 h-4" />
+              )}
+            </button>
+          )}
+
           <button
             type="button"
             onClick={() => setSubView('editor')}
@@ -1079,26 +1099,6 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
         {/* Right Action buttons */}
         <div className="flex items-center gap-2">
-          {subView === 'editor' && (
-            <button
-              type="button"
-              onClick={toggleSidebar}
-              className={`hidden sm:flex h-8 px-2.5 text-xs font-medium border rounded-btn transition-colors items-center gap-1.5 cursor-pointer ${
-                isSidebarCollapsed
-                  ? 'bg-panel border-accent text-accent'
-                  : 'bg-canvas border-border text-muted hover:text-main'
-              }`}
-              title={isSidebarCollapsed ? 'Ordnerleiste einblenden' : 'Ordnerleiste einklappen'}
-            >
-              {isSidebarCollapsed ? (
-                <PanelLeftOpen className="w-3.5 h-3.5" />
-              ) : (
-                <PanelLeftClose className="w-3.5 h-3.5" />
-              )}
-              <span>{isSidebarCollapsed ? 'Ordner anzeigen' : 'Ordner einklappen'}</span>
-            </button>
-          )}
-
           <button
             type="button"
             onClick={() => handleCreateDocument('')}