Add CLAUDE.md for project guidance and workflow documentation

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.
+
+## Project Overview
+
+- **Type**: Game service frontend agent (submodule-based monorepo)
+- **Stack**: Nuxt 3/4, TypeScript (strict), pnpm
+- **Language**: Korean (코드 리뷰, 커밋 메시지, 문서)
+
+## Commands
+
+### Development
+```bash
+pnpm install    # Install dependencies
+pnpm dev        # Run dev server
+pnpm build      # Production build
+pnpm preview    # Preview build
+```
+
+### Validation
+```bash
+pnpm build      # Verify no build errors
+pnpm typecheck  # Verify TypeScript (if configured)
+```
+
+### Submodules
+```bash
+git submodule update --init --recursive   # Initialize
+git submodule update --remote --recursive # Update all
+```
+
+## Git Workflow
+
+### Branches
+- `release` - Production (verified)
+- `dev` - Development/testing
+- Feature branches from `dev`
+
+### MR Guidelines
+- **Title**: `[Category] Description` (Feature, Fix, Refactor, Docs)
+- **Target**: `dev` first, then `release` after verification
+- **Review**: 1+ team member approval required
+
+## Context Files
+
+Additional context in `.claude/` directory:
+- `contexts/` - Nuxt patterns, TypeScript conventions
+- `skills/` - code-review, test-generator, refactor-component
+- `agents/` - debugger, refactor, performance-optimizer
+
+## Project-Specific Patterns
+
+### Common Nuxt Issues
+- Hydration mismatch → Use `<ClientOnly>`
+- useFetch infinite loop → Check watch/immediate/key options
+
+### Key Conventions
+- Use Composition API with `<script setup lang="ts">`
+- Composables for reusable logic
+- Pinia for complex state management
+- Always type API responses: `useFetch<Type>()`