docs: 시스템 아키텍처 및 명령어 문서 추가

- COMMAND.md: 다양한 명령어와 설명 추가
- .claude/commands/design/1-system-architecture: 시스템 아키텍처 관련 문서 삭제
- .claude/commands/sc: 코드 분석, 빌드, 클린업, 설계, 문서화, 추정, 설명, Git 작업, 구현, 개선, 테스트, 문제 해결, 워크플로우 생성 등 다양한 명령어 문서 추가

.claude/commands/sc/cleanup.md

@@ -0,0 +1,34 @@
+---
+allowed-tools: [Read, Grep, Glob, Bash, Edit, MultiEdit]
+description: "Clean up code, remove dead code, and optimize project structure"
+---
+
+# /sc:cleanup - Code and Project Cleanup
+
+## Purpose
+Systematically clean up code, remove dead code, optimize imports, and improve project structure.
+
+## Usage
+```
+/sc:cleanup [target] [--type code|imports|files|all] [--safe|--aggressive]
+```
+
+## Arguments
+- `target` - Files, directories, or entire project to clean
+- `--type` - Cleanup type (code, imports, files, all)
+- `--safe` - Conservative cleanup (default)
+- `--aggressive` - More thorough cleanup with higher risk
+- `--dry-run` - Preview changes without applying them
+
+## Execution
+1. Analyze target for cleanup opportunities
+2. Identify dead code, unused imports, and redundant files
+3. Create cleanup plan with risk assessment
+4. Execute cleanup operations with appropriate safety measures
+5. Validate changes and report cleanup results
+
+## Claude Code Integration
+- Uses Glob for systematic file discovery
+- Leverages Grep for dead code detection
+- Applies MultiEdit for batch cleanup operations
+- Maintains backup and rollback capabilities