docs: add Material for MkDocs documentation site (English + Japanese)

Add a documentation website under website/, built from README.md and
README-Japanese.md and laid out with top-tab topics and a left sidebar (same
style as the Hayabusa docs). Designed to be hosted free on GitHub Pages.

- Pages: Overview (About, Features, Screenshots), Getting Started, Commands
  (Command List, Command Usage), Resources (Companion Projects, Other
  Resources, Changelog, Contributing)
- Custom landing page, theme, click-to-zoom screenshots
- Changelog synced from CHANGELOG.md at build time
- 15-language switcher via mkdocs-static-i18n: English + Japanese full content;
  the other 13 localize the UI and fall back to English until translated
- .github/workflows/docs.yml builds (mkdocs --strict) + deploys to GitHub Pages

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

website/docs/overview/features.ja.md

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+# 機能
+- Windows Event Log Audit policyに対する評価
+- 主要なWindowsイベントログ監査設定ガイドに基づくチェック
+- Windows Event Logの監査設定を、実際のSigmaルールの検知範囲に基づいて評価
+- Windows Event Logのファイルサイズを監査し、推奨サイズを提案
+- 推奨されるWindowsイベントログ監査ポリシーとファイルサイズの設定

website/docs/overview/features.md

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+# Features
+- Auditing Windows event log audit policy settings.
+- Checking **based on the major Windows event log audit configuration guidelines**.
+- Checking Windows event log audit settings based on **real-world Sigma rule detectability**.
+- Auditing of Windows event log file sizes and suggestions for the recommended size.
+- Setting recommended Windows event log audit policy and file sizes.

website/docs/overview/index.ja.md

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+# WELAについて
+**WELA（Windows Event Log Analyzer、ゑ羅）** は、Windowsイベントログの設定とログサイズを監査するツールです。
+Windowsイベントログは、DFIR（デジタルフォレンジックおよびインシデント対応）に不可欠な情報源であり、システムの動作やセキュリティイベントを可視化します。
+**しかし、デフォルト設定では、不十分なログサイズ、監査設定によって、脅威の検知漏れを引き起こす**可能性があります。
+WELAはこうした課題を洗い出し、Windowsイベントログ設定改善のための実用的な提案を行います。
+また、**実際のSigmaルールの検知範囲に基づいてWindowsイベントログ設定を評価**し、現状の設定で何が検知できるかを把握できます。

website/docs/overview/index.md

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+# About WELA
+**WELA (Windows Event Log Analyzer, ゑ羅)** is a tool for auditing Windows event log settings.
+Windows event logs are a vital source of information for Digital Forensics and Incident Response (DFIR), providing visibility into system activity and security events.
+**Unfortunately, default configurations often lead to problems such as limited log retention, insufficient audit policies, and blind spots that reduce detection capability**.
+WELA helps uncover these weaknesses and offers practical recommendations to improve audit settings and enhance security visibility.
+WELA also assesses log configurations **based on real-world Sigma rule coverage**, allowing users to evaluate what can or cannot be detected under current the settings.

website/docs/overview/screenshots.ja.md

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+# スクリーンショット
+
+## スタートアップ
+![WELA Startup](../assets/screenshots/startup.png)
+
+## audit-settings (stdout)
+![WELA Stdout](../assets/screenshots/stdout.png)
+## audit-settings (gui)
+![WELA GUI](../assets/screenshots/gui.png)
+
+## audit-settings (table)
+![WELA Table](../assets/screenshots/table.png)
+
+## audit-settings (mitre-attack-navigator)
+![WELA Mitre Attack Navigator](../assets/screenshots/mitre.png)
+
+## audit-filesize
+![WELA FileSize](../assets/screenshots/filesize.png)
+
+## configure
+![WELA Configure](../assets/screenshots/configure.png)

website/docs/overview/screenshots.md

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+# Screenshots
+
+## Startup Help Menu
+![WELA Startup](../assets/screenshots/startup.png)
+
+## audit-settings (terminal output)
+![WELA Stdout](../assets/screenshots/stdout.png)
+## audit-settings (GUI)
+![WELA GUI](../assets/screenshots/gui.png)
+
+## audit-settings (table)
+![WELA Table](../assets/screenshots/table.png)
+
+## audit-settings (mitre-attack-navigator)
+![WELA Mitre Attack Navigator](../assets/screenshots/mitre.png)
+
+## audit-filesize
+![WELA FileSize](../assets/screenshots/filesize.png)
+
+## configure
+![WELA Configure](../assets/screenshots/configure.png)