feat(core): completely remove the dependence on EditorHost (#13110)

Close [AI-260](https://linear.app/affine-design/issue/AI-260)

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

* **New Features**
* Added theme support to AI chat and message components, enabling
dynamic theming based on the current app theme.
* Introduced a reactive theme signal to the theme service for improved
theme handling.
* Integrated notification and theme services across various AI chat,
playground, and message components for consistent user experience.

* **Refactor**
* Simplified component APIs by removing dependencies on editor host and
related properties across AI chat, message, and tool components.
* Centralized and streamlined clipboard and markdown conversion
utilities, reducing external dependencies.
* Standardized the interface for context file addition and improved type
usage for better consistency.
* Reworked notification service to a class-based implementation for
improved encapsulation.
* Updated AI chat components to use injected notification and theme
services instead of host-based retrieval.

* **Bug Fixes**
* Improved reliability of copy and notification actions by decoupling
them from editor host dependencies.

* **Chores**
* Updated and cleaned up internal imports and removed unused properties
to enhance maintainability.
  * Added test IDs for sidebar close button to improve test reliability.
  * Updated test prompts in end-to-end tests for consistency.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/affine-cloud-copilot/e2e/utils/chat-panel-utils.ts

@@ -37,7 +37,7 @@ export class ChatPanelUtils {
   }
 
   public static async closeChatPanel(page: Page) {
-    await page.getByTestId('right-sidebar-toggle').click({
+    await page.getByTestId('right-sidebar-close').click({
       delay: 200,
     });
     await expect(page.getByTestId('sidebar-tab-content-chat')).toBeHidden();