feat(gtm-guardian): Reorganize skill with dual-platform structure

- Add desktop/ directory for Claude Desktop (Phase 1-5: analysis, design, docs)
- Add code/ directory for Claude Code (Phase 6-7: automation, audit)
- Create SKILL.md with YAML frontmatter for Desktop compatibility
- Create CLAUDE.md for Code automation workflows
- Organize references by platform scope with shared files duplicated
- Add templates for tagging plan and event taxonomy
- Include README.md with overview and usage guide

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

custom-skills/22-gtm-guardian/code/references/datalayer-schema.md

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+# DataLayer Schema Reference
+
+GA4 권장 이벤트 기반 DataLayer 스키마 정의.
+
+## Core Principles
+
+1. GTM 스니펫 이전에 dataLayer 초기화
+2. 이벤트 발생 시점에 push (사전 아님)
+3. ecommerce 객체는 push 전 clear 필수
+4. PII 데이터 직접 수집 금지
+
+## Base Structure
+
+### Page Load
+```javascript
+window.dataLayer = window.dataLayer || [];
+dataLayer.push({
+  'event': 'page_data',
+  'page': {
+    'type': 'home|category|product|cart|checkout|thankyou|content|search',
+    'name': 'Page Name',
+    'category': 'Category/Subcategory',
+    'language': 'ko'
+  },
+  'user': {
+    'status': 'logged_in|logged_out',
+    'id': 'hashed_user_id',           // SHA256, 로그인 시에만
+    'type': 'new|returning|member|guest',
+    'loginMethod': 'email|kakao|naver|google'
+  }
+});
+```
+
+## E-commerce Events
+
+### view_item
+```javascript
+dataLayer.push({ ecommerce: null });
+dataLayer.push({
+  'event': 'view_item',
+  'ecommerce': {
+    'currency': 'KRW',
+    'value': 29000,
+    'items': [{
+      'item_id': 'SKU_12345',
+      'item_name': 'Product Name',
+      'item_brand': 'Brand Name',
+      'item_category': 'Category',
+      'item_variant': 'Blue / Large',
+      'price': 29000,
+      'quantity': 1
+    }]
+  }
+});
+```
+
+### add_to_cart
+```javascript
+dataLayer.push({ ecommerce: null });
+dataLayer.push({
+  'event': 'add_to_cart',
+  'ecommerce': {
+    'currency': 'KRW',
+    'value': 29000,
+    'items': [{
+      'item_id': 'SKU_12345',
+      'item_name': 'Product Name',
+      'price': 29000,
+      'quantity': 1
+    }]
+  }
+});
+```
+
+### begin_checkout
+```javascript
+dataLayer.push({ ecommerce: null });
+dataLayer.push({
+  'event': 'begin_checkout',
+  'ecommerce': {
+    'currency': 'KRW',
+    'value': 58000,
+    'coupon': 'WELCOME10',
+    'items': [/* cart items */]
+  }
+});
+```
+
+### purchase
+```javascript
+dataLayer.push({ ecommerce: null });
+dataLayer.push({
+  'event': 'purchase',
+  'ecommerce': {
+    'transaction_id': 'T_20250115_001',
+    'affiliation': 'Store Name',
+    'value': 53000,
+    'tax': 4818,
+    'shipping': 3000,
+    'currency': 'KRW',
+    'coupon': 'WELCOME10',
+    'items': [{
+      'item_id': 'SKU_12345',
+      'item_name': 'Product Name',
+      'price': 29000,
+      'quantity': 1
+    }]
+  }
+});
+```
+
+## Lead Gen Events
+
+### generate_lead
+```javascript
+dataLayer.push({
+  'event': 'generate_lead',
+  'currency': 'KRW',
+  'value': 50000,
+  'lead': {
+    'source': 'contact_form|landing_page',
+    'type': 'inquiry|quote_request'
+  }
+});
+```
+
+### form_submit
+```javascript
+dataLayer.push({
+  'event': 'form_submit',
+  'form': {
+    'id': 'contact_form',
+    'name': 'Contact Us Form',
+    'type': 'contact',
+    'success': true
+  }
+});
+```
+
+## Engagement Events
+
+### login / sign_up
+```javascript
+dataLayer.push({
+  'event': 'login',  // or 'sign_up'
+  'method': 'email|kakao|naver|google'
+});
+```
+
+### search
+```javascript
+dataLayer.push({
+  'event': 'search',
+  'search_term': 'user search query',
+  'search': {
+    'results_count': 42,
+    'category': 'product|content'
+  }
+});
+```
+
+## Item Object Reference
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| item_id | string | Yes | SKU |
+| item_name | string | Yes | 상품명 |
+| price | number | Yes | 단가 |
+| quantity | number | Yes | 수량 |
+| item_brand | string | No | 브랜드명 |
+| item_category | string | No | 카테고리 |
+| item_category2-5 | string | No | 하위 카테고리 |
+| item_variant | string | No | 옵션 |
+| coupon | string | No | 쿠폰 코드 |
+| discount | number | No | 할인 금액 |
+| index | number | No | 목록 위치 |
+
+## Validation Rules
+
+```javascript
+// ✅ Correct
+'price': 29000        // number
+'quantity': 1         // number
+'currency': 'KRW'     // uppercase
+
+// ❌ Wrong
+'price': '29000'      // string
+'currency': 'krw'     // lowercase
+```
+
+### Array Limits
+- items[]: 최대 200개
+- 초과 시 분할 전송