Add AI agent guidance documentation

Added CLAUDE.md and AGENTS.md files to provide comprehensive guidance
for AI coding agents working with this repository. Documents project
architecture, essential commands, and development workflows.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: yshrsmz

AGENTS.md

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+# CLAUDE.md
+
+This file provides guidance to AI Coding Agents(Claude Code, Codex, etc) when working with code in this repository.
+
+## Project Overview
+
+Android Dagashi is a Nuxt 3-based static site that aggregates and displays Android development news and resources. The site uses GitHub Issues as a CMS, fetching data via GitHub API and generating static pages.
+
+## Architecture
+
+### Monorepo Structure (Yarn Workspaces)
+
+- **packages/site** - Main Nuxt 3 application with Vue 3, Tailwind CSS
+- **packages/site-api** - Generates JSON API files from GitHub Issues
+- **packages/site-api-github** - GitHub API integration layer
+- **packages/site-rss** - RSS feed generation
+- **packages/sns-updater** - Social media update automation
+- **packages/site-config** - Shared configuration
+- **packages/site-types** - TypeScript type definitions
+- **packages/site-common** - Shared utilities
+
+### Key Technologies
+
+- **Frontend**: Nuxt 3, Vue 3, Tailwind CSS, Pinia (state management)
+- **Build**: Yarn 4 with workspaces, TypeScript, ESLint, Prettier
+- **Deployment**: GitHub Actions → GitHub Pages (master branch)
+
+## Essential Commands
+
+```bash
+# Initial setup (requires mise and direnv)
+make bootstrap
+
+# Development workflow
+yarn install                  # Install all dependencies
+yarn api:generate             # Fetch GitHub issues and generate JSON API files
+yarn rss:generate             # Generate RSS feed
+yarn site:dev                 # Start dev server at localhost:3000
+yarn site:generate            # Build static site for production
+
+# Code quality
+yarn site:lint                # Run ESLint
+yarn site:format              # Fix ESLint issues
+
+# Social media
+yarn sns:update               # Update social media with new content
+```
+
+## Development Requirements
+
+1. **Environment Setup**:
+   - Copy `envrc.template` to `.envrc`
+   - Add GitHub Personal Access Token to `GH_READONLY_TOKEN` in `.envrc`
+   - Install direnv and allow the `.envrc` file
+
+2. **Prerequisites**:
+   - Node.js (managed via mise)
+   - Yarn 4 (via corepack)
+   - GitHub Personal Access Token (read-only permissions sufficient)
+
+## Data Flow
+
+1. GitHub Issues in AndroidDagashi/AndroidDagashi repo serve as CMS
+2. `yarn api:generate` fetches issues via GitHub API and creates JSON files in `packages/site/public/api/`
+3. Nuxt reads these JSON files during build to generate static pages
+4. Static site deployed to GitHub Pages on master branch
+
+## Configuration Files
+
+- **nuxt.config.ts** - Main Nuxt configuration, defines routes from JSON data
+- **site-config** package - Shared configuration across workspaces
+- **mise.toml** - Node.js version management
+- **.yarnrc.yml** - Yarn 4 configuration with PnP mode
+
+## Deployment
+
+GitHub Actions workflow (`.github/workflows/deploy.yml`):
+
+- Triggers on push to development branch
+- Builds static site with `nuxi build --preset github_pages`
+- Deploys to master branch for GitHub Pages hosting
+
+## Important Patterns
+
+- All API data must be generated before running dev server or building
+- The site uses static generation with pre-rendered routes based on issue IDs
+- Custom OGP meta tag generation for social sharing
+- TypeScript strict mode is enabled across all packages

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## General instruction for AI Coding Agent
+
+Read @AGENTS.md