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/_ourdigital-shared/README.md

@@ -0,0 +1,129 @@
+# OurDigital Skills - Shared Environment
+
+Shared configuration, dependencies, and environment setup for all OurDigital Claude Skills.
+
+## Quick Setup
+
+### 1. Create Virtual Environment
+
+```bash
+cd /path/to/our-claude-skills/custom-skills
+python -m venv .venv-ourdigital
+source .venv-ourdigital/bin/activate  # macOS/Linux
+```
+
+### 2. Install Dependencies
+
+```bash
+# For Claude Code environment
+pip install -r _ourdigital-shared/requirements/code.txt
+
+# For Claude Desktop environment
+pip install -r _ourdigital-shared/requirements/desktop.txt
+
+# Or install as package
+pip install -e _ourdigital-shared/
+```
+
+### 3. Configure Environment Variables
+
+```bash
+# Copy template
+cp _ourdigital-shared/.env.ourdigital.template ~/.env.ourdigital
+
+# Edit with your credentials
+nano ~/.env.ourdigital
+```
+
+### 4. Set Up Credentials Directory
+
+```bash
+mkdir -p ~/.ourdigital/credentials
+# Add your credential files:
+# - ~/.ourdigital/credentials/notion.json
+# - ~/.ourdigital/credentials/ghost.json
+# - ~/.ourdigital/credentials/google.json
+```
+
+## Directory Structure
+
+```
+_ourdigital-shared/
+├── pyproject.toml              # Package configuration
+├── .env.ourdigital.template    # Environment variables template
+├── requirements/
+│   ├── base.txt                # Common dependencies
+│   ├── desktop.txt             # Desktop-specific
+│   └── code.txt                # Code-specific
+├── config/
+│   └── ourdigital.yaml         # Global configuration
+└── README.md                   # This file
+```
+
+## Configuration
+
+### Environment Variables
+
+Key variables in `.env.ourdigital`:
+
+| Variable | Description |
+|----------|-------------|
+| `OURDIGITAL_ENV` | Environment (development/production) |
+| `NOTION_API_TOKEN` | Notion integration token |
+| `NOTION_WORKING_WITH_AI_DB` | Primary Notion database ID |
+| `GHOST_BLOG_ADMIN_KEY` | Ghost CMS admin API key |
+
+### Config File
+
+`config/ourdigital.yaml` contains:
+- Brand settings (name, tagline, values)
+- Channel configurations
+- Color palette
+- Typography settings
+- Skill numbering conventions
+- Export paths
+
+## Usage in Skills
+
+### Loading Configuration
+
+```python
+import yaml
+from pathlib import Path
+
+def load_config():
+    config_path = Path(__file__).parent.parent / "_ourdigital-shared/config/ourdigital.yaml"
+    with open(config_path) as f:
+        return yaml.safe_load(f)
+
+config = load_config()
+print(config['brand']['tagline'])
+```
+
+### Loading Environment
+
+```python
+from dotenv import load_dotenv
+import os
+
+load_dotenv(os.path.expanduser("~/.env.ourdigital"))
+
+notion_token = os.getenv("NOTION_API_TOKEN")
+```
+
+## Skill Numbering
+
+| Range | Category |
+|-------|----------|
+| 01-09 | OurDigital Core (brand, blog, journal, research, etc.) |
+| 10 | Meta (skill-creator) |
+| 11-19 | SEO Tools |
+| 20-29 | GTM/Analytics Tools |
+| 31-39 | Notion Tools |
+| 40-49 | Jamie Clinic Tools |
+
+## Version
+
+- Package Version: 1.0.0
+- Python Requirement: >= 3.11
+- Author: OurDigital (Andrew Yim)