fix(editor): callout delete merge and slash menu (#13597)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- New Features
- Press Enter inside a callout splits the paragraph at the cursor into a
new focused paragraph.
- Clicking an empty callout inserts and focuses a new paragraph; emoji
menu behavior unchanged.
- New command to convert a callout paragraph to callout/selection flow
for Backspace handling.
  - New native API: ShareableContent.isUsingMicrophone(processId).

- Bug Fixes
- Backspace inside callout paragraphs now merges or deletes text
predictably and selects the callout when appropriate.

- Style
- Callout layout refined: top-aligned content and adjusted emoji
spacing.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/affine-local/e2e/blocksuite/callout/callout.spec.ts

@@ -3,7 +3,6 @@ import {
   pressArrowUp,
   pressBackspace,
   pressEnter,
-  undoByKeyboard,
 } from '@affine-test/kit/utils/keyboard';
 import { openHomePage } from '@affine-test/kit/utils/load-page';
 import {
@@ -30,7 +29,7 @@ test('add callout block using slash menu and change emoji', async ({
   await expect(emoji).toContainText('😀');
 
   const paragraph = page.locator('affine-callout affine-paragraph');
-  await expect(paragraph).toHaveCount(1);
+  await expect(paragraph).toHaveCount(2);
 
   const vLine = page.locator('affine-callout v-line');
   await expect(vLine).toHaveCount(2);
@@ -50,22 +49,6 @@ test('add callout block using slash menu and change emoji', async ({
   await expect(emoji).toContainText('😆');
 });
 
-test('disable slash menu in callout block', async ({ page }) => {
-  await type(page, '/callout\n');
-  const callout = page.locator('affine-callout');
-  const emoji = page.locator('affine-callout .affine-callout-emoji');
-  await expect(callout).toBeVisible();
-  await expect(emoji).toContainText('😀');
-
-  await type(page, '/');
-  const slashMenu = page.locator('.slash-menu');
-  await expect(slashMenu).not.toBeVisible();
-  await undoByKeyboard(page);
-  await undoByKeyboard(page);
-  await type(page, '/');
-  await expect(slashMenu).toBeVisible();
-});
-
 test('press backspace after callout block', async ({ page }) => {
   await pressEnter(page);
   await pressArrowUp(page);
@@ -96,7 +79,7 @@ test('press backspace in callout block', async ({ page }) => {
   expect(await callout.count()).toBe(1);
 
   await pressBackspace(page);
-  await expect(paragraph).toHaveCount(2);
+  await expect(paragraph).toHaveCount(1);
   await expect(callout).toHaveCount(1);
 
   await pressBackspace(page);