Pilot QEP-5's three channels on QuantEcon.py

QuantEcon.py is the pilot repository for the QEP-5 rollout: it already has an AGENTS.md, it is where the QEP's field test ran, and it takes the most outside pull requests. On 2026-09-14 none of its CONTRIBUTING.md, docs/source/contributing.rst, or AGENTS.md mentions AI use or the Assisted-by: line.

To do

• CONTRIBUTING.md: add the Code of AI Use section with the same content as the org default (the org default does not reach this repository because it has its own file). Mirror it in docs/source/contributing.rst, which is the rendered guide the file points to.
• AGENTS.md: run qe gh agents sync QuantEcon/QuantEcon.py once QuantEcon/cli#50 ships, and confirm qe gh agents check passes. Do not paste the block by hand.
• Ask comment: add the caller workflow for the reusable workflow from QuantEcon/project-qep5#8, and confirm on the next external pull request without an Assisted-by: line that it posts once, with the welcome wording, and not on organisation members or automated pull requests.
• Confirm the org-default pull-request template appears on a new pull request here (this repository has no template of its own).

Done when all three channels are live, qe gh agents check passes, and the first ask comment has fired and been answered. Record the first ask here with a link; the month of measurement then starts.

Start with CONTRIBUTING.md, docs/source/contributing.rst, and AGENTS.md, then review the org default and the reusable workflow from QuantEcon/project-qep5#8. After QuantEcon/cli#50 ships, run qe gh agents sync QuantEcon/QuantEcon.py and qe gh agents check; done means all three channels are live, the check passes, and the first ask comment is posted once, answered, and recorded here.