refactor: Reorganize repository structure for optimal learning path

Reorder folders based on learning dependencies, complexity, and frequency of use:
- 01-slash-commands (unchanged) - Quick wins for beginners
- 02-memory (was 03) - Essential foundation
- 03-skills (was 05) - Auto-invoked capabilities
- 04-subagents (was 02) - Task delegation
- 05-mcp (was 04) - External integration
- 06-hooks (was 07) - Event automation
- 07-plugins (was 06) - Bundled solutions
- 08-checkpoints (unchanged) - Safe experimentation
- 09-advanced-features (unchanged) - Power user tools

Documentation improvements:
- Add LEARNING-ROADMAP.md with detailed milestones and exercises
- Simplify README.md for better scannability
- Consolidate Quick Start and Getting Started sections
- Combine Feature Comparison and Use Case Matrix tables
- Reorder README sections: Learning Path → Quick Reference → Getting Started
- Update all cross-references across module READMEs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

09-advanced-features/README.md

@@ -1038,9 +1038,13 @@ Create `.claude/config.json` in your project:
 For more information about Claude Code and related features, see:
 
 - [Main Claude Code Guide](../README.md)
-- [Claude Code Basics](../01-basics/)
-- [Advanced Code Analysis](../02-code-analysis/)
-- [Collaboration Features](../03-collaboration/)
-- [Troubleshooting Guide](../troubleshooting.md)
+- [Slash Commands](../01-slash-commands/)
+- [Memory](../02-memory/)
+- [Skills](../03-skills/)
+- [Subagents](../04-subagents/)
+- [MCP](../05-mcp/)
+- [Hooks](../06-hooks/)
+- [Plugins](../07-plugins/)
+- [Checkpoints](../08-checkpoints/)
 - [Claude Documentation](https://docs.claude.com)
 - [MCP GitHub Servers](https://github.com/modelcontextprotocol/servers)