feat(core): embedding status tooltip (#12382)

### TL;DR

feat: display embedding tip for ai chat

![截屏2025-05-20 10.35.11.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/MyktQ6Qwc7H6TiRCFoYN/c3a4fe47-1995-4ec0-bde0-ddbe19ce95a2.png)

> CLOSE BS-3051

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

- **New Features**
  - Introduced an embedding status tooltip in the AI chat interface, providing real-time feedback on embedding progress for your workspace.
  - Added support for embedding status tracking within the AI provider and client services.
- **Style**
  - Updated the AI chat footer layout for improved clarity and usability.
- **Tests**
  - Added an end-to-end test to ensure the embedding status tooltip displays correctly.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/affine-cloud-copilot/e2e/basic/chat.spec.ts

@@ -17,6 +17,20 @@ test.describe('AIBasic/Chat', () => {
     await expect(page.getByTestId('ai-onboarding')).toBeVisible();
   });
 
+  test('should display embedding status tooltip', async ({
+    loggedInPage: page,
+  }) => {
+    const check = await page.getByTestId(
+      'ai-chat-embedding-status-tooltip-check'
+    );
+    await expect(check).toBeVisible();
+
+    await check.hover();
+    const tooltip = await page.getByTestId('ai-chat-embedding-status-tooltip');
+    await expect(tooltip).toBeVisible();
+    await expect(tooltip).toHaveText(/Results will improve after embedding/i);
+  });
+
   test(`should send message and receive AI response:
         - send message
         - AI is loading