feat: Add OurDigital custom skills package (10 skills)

Complete implementation of OurDigital skills with dual-platform support
(Claude Desktop + Claude Code) following standardized structure.

Skills created:
- 01-ourdigital-brand-guide: Brand reference & style guidelines
- 02-ourdigital-blog: Korean blog drafts (blog.ourdigital.org)
- 03-ourdigital-journal: English essays (journal.ourdigital.org)
- 04-ourdigital-research: Research prompts & workflows
- 05-ourdigital-document: Notion-to-presentation pipeline
- 06-ourdigital-designer: Visual/image prompt generation
- 07-ourdigital-ad-manager: Ad copywriting & keyword research
- 08-ourdigital-trainer: Training materials & workshop planning
- 09-ourdigital-backoffice: Quotes, proposals, cost analysis
- 10-ourdigital-skill-creator: Meta skill for creating new skills

Features:
- YAML frontmatter with "ourdigital" or "our" prefix triggers
- Standardized directory structure (code/, desktop/, shared/, docs/)
- Shared environment setup (_ourdigital-shared/)
- Comprehensive reference documentation
- Cross-skill integration support

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

custom-skills/07-ourdigital-ad-manager/shared/references/platform-specs.md

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+# Platform Specifications
+
+Character limits and format requirements for advertising platforms.
+
+## Google Ads
+
+### Responsive Search Ads (RSA)
+
+| Element | Limit | Notes |
+|---------|-------|-------|
+| Headlines | 30 chars × 15 max | Min 3, recommended 10+ |
+| Descriptions | 90 chars × 4 max | Min 2, recommended 4 |
+| Display URL paths | 15 chars × 2 | Optional |
+| Final URL | 2048 chars | Required |
+
+### Display Ads
+
+| Format | Dimensions | File Size |
+|--------|------------|-----------|
+| Leaderboard | 728×90 | 150KB |
+| Medium Rectangle | 300×250 | 150KB |
+| Wide Skyscraper | 160×600 | 150KB |
+| Large Rectangle | 336×280 | 150KB |
+| Responsive | Various | 150KB |
+
+### Performance Max
+
+| Asset Type | Specs |
+|------------|-------|
+| Short headline | 30 chars |
+| Long headline | 90 chars |
+| Description | 90 chars |
+| Business name | 25 chars |
+| Images | 1200×628, 1200×1200, 628×628 |
+| Videos | 10 sec+ recommended |
+
+## Naver Search Ads
+
+### 파워링크
+
+| Element | Limit |
+|---------|-------|
+| 제목 | 25자 (한글 기준) |
+| 설명 | 45자 |
+| 표시 URL | 도메인만 |
+
+### 브랜드검색광고
+
+| Element | Limit |
+|---------|-------|
+| 메인 제목 | 15자 |
+| 서브 제목 | 30자 |
+| 설명문 | 100자 |
+| 이미지 | 200×200 이상 |
+
+### 확장소재
+
+| Type | Limit |
+|------|-------|
+| 확장 제목 | 25자 |
+| 추가 설명 | 20자 × 2개 |
+| 서브링크 | 제목 15자, URL |
+| 가격정보 | 15자 + 금액 |
+
+## Meta (Facebook/Instagram)
+
+### Feed Ads
+
+| Element | Limit | Recommended |
+|---------|-------|-------------|
+| Primary text | 125 chars visible | 40-50 chars |
+| Headline | 40 chars | 25-30 chars |
+| Description | 30 chars | Optional |
+| Link description | 30 chars | |
+
+### Stories Ads
+
+| Element | Specs |
+|---------|-------|
+| Aspect ratio | 9:16 |
+| Image | 1080×1920 |
+| Video | 15 sec max |
+| Text overlay | Minimal (20% rule relaxed) |
+
+### Reels Ads
+
+| Element | Specs |
+|---------|-------|
+| Aspect ratio | 9:16 |
+| Duration | 15-60 sec |
+| Caption | 72 chars visible |
+
+## LinkedIn Ads
+
+### Sponsored Content
+
+| Element | Limit |
+|---------|-------|
+| Introductory text | 600 chars (150 visible) |
+| Headline | 200 chars |
+| Description | 300 chars |
+| Image | 1200×627 |
+
+### Message Ads
+
+| Element | Limit |
+|---------|-------|
+| Subject line | 60 chars |
+| Message body | 1500 chars |
+| CTA | 20 chars |
+
+### Text Ads
+
+| Element | Limit |
+|---------|-------|
+| Headline | 25 chars |
+| Description | 75 chars |
+| Image | 100×100 |
+
+## Twitter (X) Ads
+
+### Promoted Tweets
+
+| Element | Limit |
+|---------|-------|
+| Tweet text | 280 chars |
+| Card headline | 70 chars |
+| Card description | 200 chars |
+| Website URL | Included |
+
+### Image Specs
+
+| Format | Specs |
+|--------|-------|
+| Single image | 1200×675 (1.91:1) |
+| Multi-image | 600×335 each |
+| Carousel | 800×800 (1:1) |
+
+## Kakao Ads
+
+### 비즈보드
+
+| Element | Limit |
+|---------|-------|
+| 제목 | 21자 |
+| 설명 | 45자 |
+| 이미지 | 640×480 |
+
+### 카카오모먼트
+
+| Type | Specs |
+|------|-------|
+| 네이티브 이미지 | 1200×628 |
+| 네이티브 동영상 | 1920×1080 |
+| 텍스트 | 45자 |
+
+## YouTube Ads
+
+### In-Stream Ads
+
+| Type | Duration | Skip |
+|------|----------|------|
+| Skippable | Any length | After 5 sec |
+| Non-skippable | 15-20 sec | No |
+| Bumper | 6 sec max | No |
+
+### Discovery Ads
+
+| Element | Limit |
+|---------|-------|
+| Headline | 25 chars × 2 |
+| Description | 90 chars × 2 |
+| Thumbnail | 1280×720 |
+
+## Best Practices Summary
+
+### Character Count Tips
+
+1. **Stay under 80%** of max for safety margin
+2. **Front-load** key message
+3. **Test mobile** truncation points
+4. **Use abbreviations** sparingly
+
+### Image Guidelines
+
+1. **High resolution** always
+2. **Minimal text** on images (especially Meta)
+3. **Brand colors** consistent
+4. **CTA button** placement matters
+
+### Video Guidelines
+
+1. **Hook in 3 seconds**
+2. **Captions** always (85% watch muted)
+3. **Logo** early for brand recall
+4. **CTA** at end or throughout