test: migrate frontend specs to Playwright (ether/etherpad#7622)

The legacy mocha+helper specs in static/tests/frontend/ have been
silently dead since core removed the in-page jQuery test runner in
2023 (cc80db2d3). Migrate to Playwright at the new conventional
location ether/etherpad#7623 introduces:

  static/tests/frontend-new/specs/

Once that core PR lands and a new release of this plugin ships, the
specs will run automatically in:
  - This plugin's own frontend-tests CI (against core+plugin).
  - Core's chrome-with-plugins CI (ether/etherpad#7609).

The legacy file is removed because it never executed and would
otherwise rot further.

Change type: patch (test-only).

Author: JohnMcLear

static/tests/frontend-new/specs/markdown.spec.ts

@@ -0,0 +1,35 @@
+import {expect, test} from '@playwright/test';
+import {clearPadContent, getPadBody, goToNewPad, selectAllText, writeToPad}
+    from 'ep_etherpad-lite/tests/frontend-new/helper/padHelper';
+
+test.beforeEach(async ({page}) => {
+  await goToNewPad(page);
+});
+
+test.describe('ep_markdown', () => {
+  test('Bold section renders the markdown class on body when "Show Markdown" is enabled',
+      async ({page}) => {
+        const padBody = await getPadBody(page);
+        await padBody.click();
+        await clearPadContent(page);
+        await writeToPad(page, 'bold');
+        await selectAllText(page);
+
+        // Apply bold via the toolbar button.
+        await page.locator('.buttonicon-bold').click();
+
+        // Toggle "Show Markdown" in pad settings.
+        // Settings popup must be open for #options-markdown to be clickable.
+        await page.locator('.buttonicon-settings').click();
+        await page.locator('#options-markdown').click({force: true});
+
+        // The pad body should gain the `markdown` class so its CSS swaps
+        // <b> for visible **bold** rendering.
+        await expect(padBody).toHaveClass(/markdown/);
+
+        // The original text content is unchanged (the rendering is purely
+        // CSS-driven; the underlying text remains "bold" without the
+        // surrounding asterisks in the document model).
+        await expect(padBody.locator('div').first()).toHaveText('bold');
+      });
+});