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 -->

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

blocksuite/affine/blocks/callout/package.json

@@ -22,6 +22,7 @@
     "@blocksuite/std": "workspace:*",
     "@blocksuite/store": "workspace:*",
     "@emoji-mart/data": "^1.2.1",
+    "@emotion/css": "^11.13.5",
     "@floating-ui/dom": "^1.6.10",
     "@lit/context": "^1.1.2",
     "@preact/signals-core": "^1.8.0",