refactor(core): ai input images display & max images count (#12395)

### TL;DR

* refactor: use horizontal scrolling to display images​
* refactor: change max images to 9
* test: add test cases for validating the maximum number of uploadable images

> CLOSE AI-6

![截屏2025-05-20 17.12.02.png](https://graphite-user-uploaded-assets-prod.s3.amazonaws.com/MyktQ6Qwc7H6TiRCFoYN/e234dd02-3bb8-4ea8-b69b-93c71b203a4e.png)

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

## Summary by CodeRabbit

- **New Features**
  - Added a notification to inform users when attempting to upload more images than allowed in the AI chat input.

- **Bug Fixes**
  - Prevented uploading more than 9 images at once in the AI chat input.

- **Style**
  - Improved image preview grid layout to display images in a single horizontally scrollable row.

- **Tests**
  - Added an end-to-end test to verify that an error message appears when too many images are uploaded.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

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

@@ -236,10 +236,9 @@ export class ChatPanelUtils {
     await this.makeChat(page, text);
   }
 
-  public static async chatWithImages(
+  public static async uploadImages(
     page: Page,
-    images: { name: string; mimeType: string; buffer: Buffer }[],
-    text: string
+    images: { name: string; mimeType: string; buffer: Buffer }[]
   ) {
     await page.evaluate(() => {
       delete window.showOpenFilePicker;
@@ -251,6 +250,14 @@ export class ChatPanelUtils {
 
     const fileChooser = await fileChooserPromise;
     await fileChooser.setFiles(images);
+  }
+
+  public static async chatWithImages(
+    page: Page,
+    images: { name: string; mimeType: string; buffer: Buffer }[],
+    text: string
+  ) {
+    await this.uploadImages(page, images);
 
     await page.waitForSelector('ai-chat-input img');
     await this.makeChat(page, text);