Fix: Add appendices A-G to navigation menu for both desktop and mobile

[Copilot]

The navigation sidebar was missing all appendices (付録A through 付録G), making it impossible to navigate to these important sections from the table of contents menu. This affected both desktop and mobile hamburger menu navigation.

Problem

The populateNavigation() function in website/js/app.js only recognized two markdown link formats:

• Chapter headings with ### prefix
• Direct chapter references with ## prefix

However, appendices use a different format in the table of contents:

- **[付録A 美しいソースコードのための七箇条](appendix-a.md)** - 詳細版・実践ガイド
- **[付録B 命名規則とコーディング規約例](appendix-b.md)** - 多言語対応

This format was not matched by existing regex patterns, causing all appendices to be excluded from navigation.

Solution

Added a new regex pattern to detect and parse appendix links:

// Match appendix links like - **[付録A 美しいソースコードのための七箇条](appendix-a.md)** - 詳細版・実践ガイド
const appendixMatch = line.match(/^\s*-\s*\*\*\[([^\]]+)\]\(([^)]+)\)\*\*/);
if (appendixMatch) {
    const title = appendixMatch[1];
    const filename = decodeURIComponent(appendixMatch[2]).replace('.md', '');
    navHtml += `<li><a href="#" onclick="loadPage('${filename}')">${title}</a></li>`;
}

This minimal 8-line addition preserves all existing functionality while adding support for appendix navigation.

Testing

✅ All appendices A-G now appear in navigation menu
✅ Clicking appendices correctly loads content
✅ Active state updates properly when navigating
✅ Mobile responsive design preserved
✅ Existing chapter navigation unaffected

Desktop View:

Mobile View:

Fixes #113.

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[Copilot]

Pull Request Overview

This PR fixes a navigation issue where appendices A-G were missing from both desktop and mobile navigation menus. The fix adds a new regex pattern to detect appendix links in the table of contents markdown, enabling proper navigation to these important sections.

Key Changes

• Added regex pattern to parse appendix links with bold formatting and descriptions
• Extended navigation population logic to include appendices alongside existing chapters
• Maintained backward compatibility with existing chapter navigation patterns

[Copilot]

The appendix handling logic duplicates the exact same title extraction and HTML generation pattern used for directChapterMatch above. Consider extracting this into a helper function to reduce code duplication and improve maintainability.