refactor: Reorganize skill numbering and update documentation

Skill Numbering Changes:
- 01-03: OurDigital core (was 30-32)
- 31-32: Notion tools (was 01-02)
- 99_archive: Renamed from _archive for sorting

New Files:
- AGENTS.md: Claude Code agent routing guide
- requirements.txt for 00-claude-code-setting, 32-notion-writer, 43-jamie-youtube-manager

Documentation Updates:
- CLAUDE.md: Updated skill inventory (23 skills)
- AUDIT_REPORT.md: Current completion status (91%)
- Archived REFACTORING_PLAN.md (most tasks complete)

Removed:
- ga-agent-skills/ (moved to separate repo ~/Project/dintel-ga4-agent)

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

custom-skills/32-notion-writer/code/scripts/.env.example

@@ -0,0 +1,4 @@
+# Notion API Configuration
+# Get your integration token from: https://www.notion.so/my-integrations
+
+NOTION_API_KEY=secret_your_notion_integration_token_here