Migrate `high-dim-data` to this repo

[mmcky]

(Low Priority)

We should migrate https://github.com/QuantEcon/high_dim_data to be hosted in this repo in a folder high_dimension perhaps.

[mmcky]

Status — 2026-07-16

Still open, and still PLAN Phase 3 — but high_dim_data is in materially better shape for the fold than it was, so noting what changed.

Its branch-only file is gone. SCF_plus_mini_no_weights.csv existed only on the update_scf_noweights branch, and lecture-python-intro/lectures/mle.md had been reading it from there since 2023. That branch is now merged (QuantEcon/high_dim_data#6, open since 2023-04-28) and deleted, and all four consuming repos are repointed at main — QuantEcon/meta#337 risk 1, now closed. So a fold no longer has to reason about a branch-only file with live consumers.

The .gitattributes problem is unchanged and is the real work here. high_dim_data carries a blanket *.csv filter=lfs rule, which is why mle.md needs an LFS-aware URL at all. This repo deliberately will not inherit that rule (AGENTS.md), so the fold has to decide per-path LFS for the SCF pair — which is exactly #1.

Sequencing constraint worth restating (from PLAN.md): enabling LFS on a path breaks every raw.githubusercontent.com URL for it — those URLs return pointer text, not data, so consumers fail with a confusing parse error rather than a 404. Verified live against SCF_plus_mini.csv on high_dim_data main today. Do not LFS-track an existing file until its consumers use a form that survives it (github.com/{org}/{repo}/raw/{ref}/… interim, or Pages final).

The cross_section/ set (Forbes ×2, cities ×2) plus the SCF pair are pilot P3 of QuantEcon/meta#338 — that pilot is where this fold gets executed and tested, rather than as a separate migration.