refactor(editor): new icon picker (#13658)

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

* **New Features**
* In-tree icon picker for Callout blocks (emoji, app icons, images) with
popup UI and editor-wide extension/service.
* Callout toolbar adds background color presets, an icon-picker action,
and a destructive Delete action.

* **Refactor**
* Replaced legacy emoji workflow with icon-based rendering, updated
state, styling, and lifecycle for callouts.

* **Tests**
  * Updated callout E2E to reflect new default icon and picker behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: L-Sun <zover.v@gmail.com>

blocksuite/affine/model/src/blocks/callout/callout-model.ts

@@ -1,3 +1,4 @@
+import type { IconData } from '@blocksuite/affine-shared/services';
 import {
   BlockModel,
   BlockSchemaExtension,
@@ -8,15 +9,17 @@ import {
 import type { BlockMeta } from '../../utils/types';
 
 export type CalloutProps = {
-  emoji: string;
+  icon?: IconData;
   text: Text;
+  backgroundColorName?: string;
 } & BlockMeta;
 
 export const CalloutBlockSchema = defineBlockSchema({
   flavour: 'affine:callout',
   props: (internal): CalloutProps => ({
-    emoji: '😀',
+    icon: { type: 'emoji', unicode: '💡' } as IconData,
     text: internal.Text(),
+    backgroundColorName: 'grey',
     'meta:createdAt': undefined,
     'meta:updatedAt': undefined,
     'meta:createdBy': undefined,