Improved Development Log browsing and static indexing

Reworked the Development Log browsing structure and clarified the roles of the main log list and individual detail pages. The standard log view now shows a short preview instead of the full body while keeping the existing five-entry pagination, making it easier to quickly scan recent development updates.

Added full log index views accessible from the Game Development, Tool Development, and AscenderAI Development section headings. For Tool Development, past logs can also be browsed by subcategory, such as Manual Grid Authoring Tool and the official website. Each log title links to its Japanese or English static detail page, where the full entry can be read.

The Dev Log JSON remains the single source of truth, while the generation script now produces Japanese and English static HTML pages and updates the sitemap automatically. This improves navigation for human visitors while also making individual log URLs and full content easier for search engines and AI crawlers to discover without relying on JavaScript execution.

The individual detail page styling was also improved by resolving a CSS class collision between the page background and the article content wrapper. The full article is now displayed on a consistent brown card background, preventing the tavern background image from showing through the text area and improving readability in both Japanese and English.