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/91-multi-agent-guide/skills/multi-agent-guide/examples/minimal-setup/README.md

@@ -0,0 +1,67 @@
+# Minimal Multi-Agent Setup Example
+
+This example shows the minimum files needed for a 2-agent setup (Claude + Codex).
+
+## Directory Structure
+
+```
+project/
+├── .agent-state/
+│   ├── tasks.yaml
+│   └── locks.yaml
+├── tools/
+│   └── check-ownership.py
+├── AGENTS.md
+├── GUARDRAILS.md
+└── CLAUDE.md
+```
+
+## Files Created
+
+1. **AGENTS.md** - Basic agent hierarchy (Claude lead, Codex sub-agent)
+2. **GUARDRAILS.md** - Simplified ownership matrix
+3. **CLAUDE.md** - Lead agent directive
+4. **.agent-state/** - Task and lock management
+5. **tools/check-ownership.py** - Verification script
+
+## Setup Steps
+
+1. Create directories:
+   ```bash
+   mkdir -p .agent-state tools
+   ```
+
+2. Copy templates (customize as needed):
+   ```bash
+   # From skill templates
+   cp templates/agents-md.md AGENTS.md
+   cp templates/guardrails-md.md GUARDRAILS.md
+   cp templates/claude-md.md CLAUDE.md
+   cp templates/tasks-yaml.yaml .agent-state/tasks.yaml
+   cp templates/locks-yaml.yaml .agent-state/locks.yaml
+   cp scripts/check-ownership.py tools/check-ownership.py
+   ```
+
+3. Set environment variable:
+   ```bash
+   export SEO_AGENT_AUTHOR=claude
+   ```
+
+4. Verify setup:
+   ```bash
+   python tools/check-ownership.py --verify-setup
+   ```
+
+## Ownership Matrix (Minimal)
+
+| Agent | Owns |
+|-------|------|
+| Claude | `src/`, `CLAUDE.md`, `AGENTS.md`, `GUARDRAILS.md` |
+| Codex | `tests/`, `CODEX.md` |
+
+## Commit Format
+
+```
+[Claude] type(scope): description
+[Codex] type(scope): description
+```