fix(core): in edgeless mode, an error occurs when asking AI questions without selecting any content (#12437)

### TL;DR

fix: in edgeless mode, an error occurs when asking AI questions without selecting any content

> CLOSE AI-133

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

- **New Features**
  - Added support for asking AI input in edgeless mode when no content is selected.
  - Enhanced AI panel behavior with improved input handling and chat message sending in edgeless mode.
- **Bug Fixes**
  - Improved handling of AI chat input visibility and context extraction in edgeless mode.
- **Tests**
  - Introduced new end-to-end tests to verify chat interactions with AI in edgeless mode.
  - Centralized editor content removal logic in test utilities for better maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -484,4 +484,31 @@ test.describe('AIBasic/Chat', () => {
       },
     ]);
   });
+
+  test('should support chat with ask ai input in edgeless mode when nothing selected', async ({
+    loggedInPage: page,
+    utils,
+  }) => {
+    await utils.chatPanel.closeChatPanel(page);
+    await utils.editor.switchToEdgelessMode(page);
+    await utils.editor.removeAll(page);
+
+    await page.mouse.move(300, 300);
+    await page.mouse.down({ button: 'right' });
+    await page.mouse.move(350, 350);
+    await page.mouse.up({ button: 'right' });
+
+    await page.keyboard.type('Who are you?');
+    await page.keyboard.press('Enter');
+    await utils.chatPanel.waitForHistory(page, [
+      {
+        role: 'user',
+        content: 'Who are you?',
+      },
+      {
+        role: 'assistant',
+        status: 'success',
+      },
+    ]);
+  });
 });

tests/affine-cloud-copilot/e2e/utils/editor-utils.ts

@@ -386,14 +386,18 @@ export class EditorUtils {
     );
   }
 
+  public static async removeAll(page: Page) {
+    await selectAllByKeyboard(page);
+    await page.keyboard.press('Delete');
+  }
+
   public static async askAIWithEdgeless(
     page: Page,
     createBlock: () => Promise<void>,
     afterSelected?: () => Promise<void>
   ) {
     await this.switchToEdgelessMode(page);
-    await selectAllByKeyboard(page);
-    await page.keyboard.press('Delete');
+    await this.removeAll(page);
     await createBlock();
     await pressEscape(page, 5);
     await selectAllByKeyboard(page);