fix: ensure data-chart library is loaded on chart-types page

Side-effect-only imports were tree-shaken by Astro's build.
Use named import with explicit init() call instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: ryo-manba

docs/src/pages/docs/chart-types.astro

@@ -379,7 +379,9 @@ import DocsLayout from '../../layouts/DocsLayout.astro';
 </style>
 
 <script>
-  import '../../../../src/index.ts';
+  import dataChart from '../../../../src/index.ts';
+  // Ensure data-chart is initialized (side-effect import is tree-shaken by Astro)
+  if (!document.querySelector('.data-chart-svg')) dataChart.init();
 
   function formatHTML(html: string): string {
     let formatted = '';

docs/src/pages/ja/docs/chart-types.astro

@@ -379,7 +379,9 @@ import DocsLayout from '../../../layouts/DocsLayout.astro';
 </style>
 
 <script>
-  import '../../../../../src/index.ts';
+  import dataChart from '../../../../../src/index.ts';
+  // Ensure data-chart is initialized (side-effect import is tree-shaken by Astro)
+  if (!document.querySelector('.data-chart-svg')) dataChart.init();
 
   function formatHTML(html: string): string {
     let formatted = '';