https://openecon.ai/ 2026-02-22 weekly 1.0 https://openecon.ai/notes 2026-02-22 weekly 0.8 https://openecon.ai/projects 2026-02-22 weekly 0.8 https://openecon.ai/projects/stata-mcp 2026-02-22 monthly 0.9 https://openecon.ai/notes/sample-ai-economics 2026-02-21 monthly 0.7