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>

02-memory/directory-api-CLAUDE.md

@@ -0,0 +1,61 @@
+# API Module Standards
+
+This file overrides root CLAUDE.md for everything in /src/api/
+
+## API-Specific Standards
+
+### Request Validation
+- Use Zod for schema validation
+- Always validate input
+- Return 400 with validation errors
+- Include field-level error details
+
+### Authentication
+- All endpoints require JWT token
+- Token in Authorization header
+- Token expires after 24 hours
+- Implement refresh token mechanism
+
+### Response Format
+
+All responses must follow this structure:
+
+```json
+{
+  "success": true,
+  "data": { /* actual data */ },
+  "timestamp": "2025-11-06T10:30:00Z",
+  "version": "1.0"
+}
+```
+
+Error responses:
+```json
+{
+  "success": false,
+  "error": {
+    "code": "VALIDATION_ERROR",
+    "message": "User message",
+    "details": { /* field errors */ }
+  },
+  "timestamp": "2025-11-06T10:30:00Z"
+}
+```
+
+### Pagination
+- Use cursor-based pagination (not offset)
+- Include `hasMore` boolean
+- Limit max page size to 100
+- Default page size: 20
+
+### Rate Limiting
+- 1000 requests per hour for authenticated users
+- 100 requests per hour for public endpoints
+- Return 429 when exceeded
+- Include retry-after header
+
+### Caching
+- Use Redis for session caching
+- Cache duration: 5 minutes default
+- Invalidate on write operations
+- Tag cache keys with resource type