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/index.md

@@ -0,0 +1,33 @@
+---
+allowed-tools: [Read, Grep, Glob, Bash, Write]
+description: "Generate comprehensive project documentation and knowledge base"
+---
+
+# /sc:index - Project Documentation
+
+## Purpose
+Create and maintain comprehensive project documentation, indexes, and knowledge bases.
+
+## Usage
+```
+/sc:index [target] [--type docs|api|structure|readme] [--format md|json|yaml]
+```
+
+## Arguments
+- `target` - Project directory or specific component to document
+- `--type` - Documentation type (docs, api, structure, readme)
+- `--format` - Output format (md, json, yaml)
+- `--update` - Update existing documentation
+
+## Execution
+1. Analyze project structure and identify key components
+2. Extract documentation from code comments and README files
+3. Generate comprehensive documentation based on type
+4. Create navigation structure and cross-references
+5. Output formatted documentation with proper organization
+
+## Claude Code Integration
+- Uses Glob for systematic file discovery
+- Leverages Grep for extracting documentation patterns
+- Applies Write for creating structured documentation
+- Maintains consistency with project conventions