fix: suppression raccourcis clavier inutiles — slash menu uniquement

Les blocs (toggle, callout, outline, columns, math) n'ont plus de
raccourcis clavier. Insertion via le menu / uniquement, comme Notion.
Plus de confusion pour l'utilisateur.

memento-note/components/tiptap-columns-extension.tsx

@@ -83,19 +83,6 @@ export const ColumnsExtension = Node.create({
       },
     }
   },
-
-  addKeyboardShortcuts() {
-    return {
-      'Mod-Alt-L': () => this.editor.commands.insertContent({
-        type: this.name,
-        attrs: { cols: 2 },
-        content: [
-          { type: 'column', attrs: { index: 0 }, content: [{ type: 'paragraph' }] },
-          { type: 'column', attrs: { index: 1 }, content: [{ type: 'paragraph' }] },
-        ],
-      }),
-    }
-  },
 })
 
 function addOrDeleteCol(state: EditorState, dispatch?: (tr: Transaction) => void, type?: 'addBefore' | 'addAfter' | 'delete'): boolean {