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/estimate.md

@@ -0,0 +1,33 @@
+---
+allowed-tools: [Read, Grep, Glob, Bash]
+description: "Provide development estimates for tasks, features, or projects"
+---
+
+# /sc:estimate - Development Estimation
+
+## Purpose
+Generate accurate development estimates for tasks, features, or projects based on complexity analysis.
+
+## Usage
+```
+/sc:estimate [target] [--type time|effort|complexity|cost] [--unit hours|days|weeks]
+```
+
+## Arguments
+- `target` - Task, feature, or project to estimate
+- `--type` - Estimation type (time, effort, complexity, cost)
+- `--unit` - Time unit for estimates (hours, days, weeks)
+- `--breakdown` - Provide detailed breakdown of estimates
+
+## Execution
+1. Analyze scope and requirements of target
+2. Identify complexity factors and dependencies
+3. Apply estimation methodologies and historical data
+4. Generate estimates with confidence intervals
+5. Present detailed breakdown with risk factors
+
+## Claude Code Integration
+- Uses Read for requirement analysis
+- Leverages Glob for codebase complexity assessment
+- Applies Grep for pattern-based estimation
+- Maintains structured estimation documentation