Plan the code import from the existing Jupyteach codebase

[mmcky]

This repository is currently an empty scaffold. The Jupyteach codebase lives with @sglyon / Valorum Data and needs to be brought over. Decisions needed:

• History: transfer the existing repository into the QuantEcon org (preserves full history, stars, and existing issues) vs. pushing the code to this repo (fresh start or grafted history). If a transfer is preferred, we would delete this scaffold repo first and re-apply the README/issues on the transferred repo.
• Pre-import hygiene: audit the history for secrets (deploy credentials, API keys, institution-specific config from the NYU and PKU HSBC deployments) before anything becomes public.
• What stays behind: deployment-specific configuration for Valorum's hosted instances vs. what belongs in the open source tree.
• CI: which workflows come across, and what secrets they need re-provisioned in the QuantEcon org.

@sglyon is best placed to lead this once he has admin access.

[mmcky]

Decision: the code import will be a fresh push to this repository — no repository transfer, and the existing git history stays in the private Valorum repo.

This narrows the remaining work here to:

• Pre-import hygiene: only the current working tree needs auditing (secrets, institution-specific config for the NYU / PKU HSBC deployments) since no history comes across.
• What stays behind: deployment-specific configuration for Valorum's hosted instances vs. what belongs in the open source tree.
• CI: which workflows come across, and what secrets need provisioning in the QuantEcon org.

The option floated above about deleting this scaffold repo ahead of a transfer no longer applies — @sglyon can push the code straight onto main here (rebasing onto or replacing the scaffold commit, either is fine).