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>

07-plugins/pr-review/plugin.yaml

@@ -0,0 +1,28 @@
+---
+name: pr-review
+version: "1.0.0"
+description: Complete PR review workflow with security, testing, and docs
+author: Anthropic
+license: MIT
+tags:
+  - code-review
+  - quality
+  - security
+
+requires:
+  - claude-code: ">=1.0.0"
+
+components:
+  - type: commands
+    path: commands/
+  - type: agents
+    path: agents/
+  - type: mcp
+    path: mcp/
+  - type: hooks
+    path: hooks/
+
+config:
+  auto_load: true
+  enabled_by_default: true
+---