feat: update all 12 chapters with latest Claude Code docs (2026)

Based on official docs at code.claude.com/docs/ko/:

- what-is-claude-code: agent loop, 5 tool categories, multi-platform, checkpoints, permission modes
- install: native install (curl/PowerShell), Homebrew, WinGet, VS Code, JetBrains, Desktop App, Web
- basics: first run flow, permission modes (Shift+Tab), checkpoint/undo (Esc×2), CLI flags
- terminal: full CLI flags reference, 36 slash commands, pipe usage, terminal optimization
- prompting: 8 core principles incl. ultrathink, subagent delegation, Plan Mode workflow
- workflow: Plan Mode, checkpointing, session resume/fork, git worktrees, ultrathink, /simplify, /batch
- claude-md: auto-memory system, .claude/rules/, path-specific rules, @import, /memory command
- mcp: correct @modelcontextprotocol package names, scope levels, /mcp context cost, subagent MCP
- skill: SKILL.md directory structure, frontmatter, $ARGUMENTS, context:fork, built-in skills
- agents: built-in subagents (Explore/Plan/general-purpose), .claude/agents/, persistent memory
- project: GitHub Actions integration, GitLab CI/CD, Slack, team workflows, cost management
- advanced: Fast Mode, Remote Control, /teleport, keyboard shortcuts, settings.json, headless mode

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: M1zz