docs: add Docusaurus docs site with EN/JA i18n and GitHub Pages deploy

.cspell.yml

@@ -22,3 +22,4 @@ ignorePaths:
   - '.git'
   - '.vscode'
   - 'node_modules'
+  - 'pnpm-lock.yaml'

.cspell/dicts/project.txt

@@ -25,3 +25,4 @@ truecolor
 getrandom
 CSPRNG
 subsec
+peaceiris

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,6 +3,7 @@
 
 - [ ] Target branch is `main`
 - [ ] Status checks are passing
+- [ ] Documentation updated if user-visible behavior changed (`website/docs/`, `website/i18n/ja/`, `README.md`)
 
 ## Summary
 

.github/workflows/docs.yml

@@ -0,0 +1,48 @@
+name: Deploy docs
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: lts/*
+
+      - name: Enable pnpm via corepack
+        run: corepack enable pnpm && corepack prepare pnpm@10.28.1 --activate
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+        working-directory: website
+
+      - name: Build
+        run: pnpm build
+        working-directory: website
+
+      - uses: actions/upload-pages-artifact@v4
+        with:
+          path: website/build
+
+  deploy:
+    needs: build
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4

AGENTS.md

@@ -6,7 +6,7 @@ This file provides guidance to AI coding agents when working with code in this r
 
 - When users ask questions, answer them instead of doing the work.
 - When making changes to user-visible behavior (commands, output, storage, configuration),
-  update `docs/user-guide.md` and `README.md` accordingly.
+  update `website/docs/` (and `website/i18n/ja/`) and `README.md` accordingly.
 
 ### Shell Rules
 

README.ja.md

@@ -26,7 +26,7 @@ curl -fsSL https://raw.githubusercontent.com/23prime/backlog-cli/latest/install.
 irm https://raw.githubusercontent.com/23prime/backlog-cli/latest/install.ps1 | iex
 ```
 
-その他のインストール方法（ソースからのビルドなど）は [ユーザーガイド](docs/user-guide.ja.md#インストール) を参照してください。
+その他のインストール方法（ソースからのビルドなど）は[ドキュメント](https://23prime.github.io/backlog-cli/ja/installation)を参照してください。
 
 ## 使い方
 
@@ -44,7 +44,7 @@ irm https://raw.githubusercontent.com/23prime/backlog-cli/latest/install.ps1 | i
     bl space
     ```
 
-詳細は [ユーザーガイド](docs/user-guide.ja.md) を参照してください。
+詳細は[ドキュメント](https://23prime.github.io/backlog-cli/ja/)を参照してください。
 
 ## 開発
 

README.md

@@ -1,4 +1,4 @@
-# backlog-cli
+# Backlog CLI
 
 An unofficial CLI tool for [Nulab's Backlog](https://backlog.com).
 
@@ -26,7 +26,7 @@ curl -fsSL https://raw.githubusercontent.com/23prime/backlog-cli/latest/install.
 irm https://raw.githubusercontent.com/23prime/backlog-cli/latest/install.ps1 | iex
 ```
 
-For other installation methods (building from source, etc.), see the [User Guide](docs/user-guide.md#installation).
+For other installation methods (building from source, etc.), see the [Documentation](https://23prime.github.io/backlog-cli/installation).
 
 ## Usage
 
@@ -44,7 +44,7 @@ For other installation methods (building from source, etc.), see the [User Guide
     bl space
     ```
 
-See the [User Guide](docs/user-guide.md) for full documentation.
+See the [Documentation](https://23prime.github.io/backlog-cli/) for full documentation.
 
 ## Development