✨(frontend) preserve @ character when esc is pressed after typing it

improves user experience by keeping @ symbol after cancelling mention trigger

Signed-off-by: Cyril <c.gromoff@gmail.com>

src/frontend/apps/e2e/__tests__/app-impress/doc-editor.spec.ts

@@ -806,6 +806,12 @@ test.describe('Doc Editor', () => {
     });
     await expect(interlinkChild1).toBeVisible({ timeout: 10000 });
     await expect(interlinkChild1.locator('svg').first()).toBeVisible();
+
+    await page.keyboard.press('@');
+
+    await page.keyboard.press('Escape');
+
+    await expect(editor.getByText('@')).toBeVisible();
   });
 
   test('it checks multiple big doc scroll to the top', async ({