test(core): split and enhance copilot e2e tests (#11007)

### TL;DR

Split and enhance copilot e2e tests.

### What Changed

#### Tests Structure

The e2e tests are organized into the following categories:

1. **Basic Tests (`/basic`)**: Tests for verifying core AI capabilities including feature onboarding, authorization workflows, and basic chat interactions.
2. **Chat Interaction Tests (`/chat-with`)**: Tests for verifying the AI's interaction with various ​object types, such as attachments, images, text content, Edgeless elements, etc.
3. **AI Action Tests (`/ai-action`)**: Tests for verifying the AI's actions, such as text translation, gramma correction, etc.
4. **Insertion Tests (`/insertion`)**: Tests for verifying answer insertion functionality.

#### Tests Writing

Writing a copilot test cases is easier and clear

e.g.
```ts
test('support chat with specified doc', async ({ page, utils }) => {
  // Initialize the doc
  await focusDocTitle(page);
  await page.keyboard.insertText('Test Doc');
  await page.keyboard.press('Enter');
  await page.keyboard.insertText('EEee is a cute cat');

  await utils.chatPanel.chatWithDoc(page, 'Test Doc');

  await utils.chatPanel.makeChat(page, 'What is EEee?');
  await utils.chatPanel.waitForHistory(page, [
    {
      role: 'user',
      content: 'What is EEee?',
    },
    {
      role: 'assistant',
      status: 'success',
    },
  ]);

  const { content } = await utils.chatPanel.getLatestAssistantMessage(page);
  expect(content).toMatch(/EEee/);
});
```

#### Summary

||Cases|
|------|----|
|Before|19||
|After|151||

> Close BS-2769

tests/affine-cloud-copilot/e2e/ai-action/continue-writing.spec.ts

@@ -0,0 +1,92 @@
+import { loginUser } from '@affine-test/kit/utils/cloud';
+import { expect } from '@playwright/test';
+
+import { test } from '../base/base-test';
+
+test.describe('AIAction/ContinueWriting', () => {
+  test.beforeEach(async ({ page, utils }) => {
+    const user = await utils.testUtils.getUser();
+    await loginUser(page, user);
+    await utils.testUtils.setupTestEnvironment(page);
+    await utils.chatPanel.openChatPanel(page);
+  });
+
+  test('should support continue writing the selected content', async ({
+    page,
+    utils,
+  }) => {
+    await page.setViewportSize({ width: 1280, height: 2000 });
+    const { continueWriting } = await utils.editor.askAIWithText(
+      page,
+      'AFFiNE is a workspace with fully merged docs'
+    );
+    const { answer, responses } = await continueWriting();
+    await expect(answer).toHaveText(/,*/, { timeout: 10000 });
+    expect(responses).toEqual(new Set(['insert-below', 'replace-selection']));
+  });
+
+  test('should support continue writing the selected text block in edgeless', async ({
+    page,
+    utils,
+  }) => {
+    const { continueWriting } = await utils.editor.askAIWithEdgeless(
+      page,
+      async () => {
+        await utils.editor.createEdgelessText(
+          page,
+          'AFFiNE is a workspace with fully merged docs'
+        );
+      }
+    );
+
+    const { answer, responses } = await continueWriting();
+    await expect(answer).toHaveText(/,*/, { timeout: 10000 });
+    expect(responses).toEqual(new Set(['insert-below']));
+  });
+
+  test('should support continue writing the selected note block in edgeless', async ({
+    page,
+    utils,
+  }) => {
+    const { continueWriting } = await utils.editor.askAIWithEdgeless(
+      page,
+      async () => {
+        await utils.editor.createEdgelessNote(
+          page,
+          'AFFiNE is a workspace with fully merged docs'
+        );
+      }
+    );
+
+    const { answer, responses } = await continueWriting();
+    await expect(answer).toHaveText(/,*/, { timeout: 10000 });
+    expect(responses).toEqual(new Set(['insert-below']));
+  });
+
+  test('should show chat history in chat panel', async ({ page, utils }) => {
+    const { continueWriting } = await utils.editor.askAIWithText(
+      page,
+      'AFFiNE is a workspace with fully merged docs'
+    );
+    const { answer } = await continueWriting();
+    const insert = answer.getByTestId('answer-insert-below');
+    await insert.click();
+    await utils.chatPanel.waitForHistory(
+      page,
+      [
+        {
+          role: 'action',
+        },
+      ],
+      10000
+    );
+    const {
+      answer: panelAnswer,
+      prompt,
+      actionName,
+    } = await utils.chatPanel.getLatestAIActionMessage(page);
+    await expect(panelAnswer).toHaveText(/,*/);
+    await expect(prompt).toHaveText(/Continue the following text/);
+    await expect(actionName).toHaveText(/Continue writing/);
+  });
+});