fix(core): some artifact styles (#13020)

fix AI-299, AI-296

#### PR Dependency Tree


* **PR #13020** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

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

## Summary by CodeRabbit

* **Style**
* Improved layout alignment in the artifact preview panel for better
visual consistency.
* Enforced a minimum width for linked document banners to ensure
consistent appearance.

* **Bug Fixes**
* Updated artifact and document compose tools so that clicking an
artifact result always opens the preview panel, instead of toggling or
closing it unexpectedly.

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

packages/frontend/core/src/blocksuite/ai/components/ai-tools/artifacts-preview-panel.ts

@@ -86,6 +86,7 @@ export class ArtifactPreviewPanel extends WithDisposable(ShadowlessElement) {
     .artifact-panel-actions {
       display: flex;
       align-items: center;
+      justify-content: flex-end;
       gap: 4px;
       flex: 1;
     }

packages/frontend/core/src/blocksuite/ai/components/ai-tools/code-artifact.ts

@@ -12,11 +12,7 @@ import { property, state } from 'lit/decorators.js';
 import { classMap } from 'lit/directives/class-map.js';
 import { bundledLanguagesInfo, type ThemedToken } from 'shiki';
 
-import {
-  closePreviewPanel,
-  isPreviewPanelOpen,
-  renderPreviewPanel,
-} from './artifacts-preview-panel';
+import { renderPreviewPanel } from './artifacts-preview-panel';
 import type { ToolError } from './type';
 
 interface CodeArtifactToolCall {
@@ -331,11 +327,6 @@ export class CodeArtifactTool extends WithDisposable(ShadowlessElement) {
       };
 
       const onClick = () => {
-        if (isPreviewPanelOpen(this)) {
-          closePreviewPanel(this);
-          return;
-        }
-
         const copyHTML = async () => {
           if (this.std) {
             await navigator.clipboard

packages/frontend/core/src/blocksuite/ai/components/ai-tools/doc-compose.ts

@@ -19,11 +19,7 @@ import { css, html, nothing } from 'lit';
 import { property } from 'lit/decorators.js';
 
 import { getCustomPageEditorBlockSpecs } from '../text-renderer';
-import {
-  closePreviewPanel,
-  isPreviewPanelOpen,
-  renderPreviewPanel,
-} from './artifacts-preview-panel';
+import { renderPreviewPanel } from './artifacts-preview-panel';
 import type { ToolError } from './type';
 
 interface DocComposeToolCall {
@@ -132,11 +128,6 @@ export class DocComposeTool extends WithDisposable(ShadowlessElement) {
       );
 
       const onClick = () => {
-        if (isPreviewPanelOpen(this)) {
-          closePreviewPanel(this);
-          return;
-        }
-
         const copyMarkdown = async () => {
           await navigator.clipboard
             .writeText(result.markdown)