Seed learning_approximation and restore its four local references (blocked on action-translation#118)

[mmcky]

learning_approximation is the one lecture in the bounded-rationality suite this edition does not have. Four references to it currently point at the English edition via intersphinx (#209); once it is translated here they should become plain local {doc} references and the lecture should join _toc.yml.

How it got this way

The sync run behind #207 named learning_approximation in _toc.yml but never wrote the file. It failed the structural parity check — the engine refusing to commit corrupt output, which is the guard working — and the run committed the ToC entry anyway (action-translation#156). The same drop happened silently in #208, which wrote no ToC entry, so nothing dangled and nothing reported it.

The parity failure is deterministic and reproduces on demand:

directive count differs: source has 36, output has 35
directive #1 name changed: source line 15 has {raw}, output line 42 has {index}
target anchors diverge — missing from output: (learning_approximation)=

That is action-translation#118 — the {raw} jupyter header block and document anchor dropped from above the title.

Why it is blocked, and on what

A measurement on 2026-07-27 identified the cause: the localisation rules. Holding model (claude-sonnet-5), engine (v0.24.0) and glossary fixed and varying only --localize, the structural pass rate is 5/15 with the rules against 14/15 without (Fisher exact p = 0.002), with every failure carrying the signature above. So seeding this lecture today with default settings is roughly a one-in-three proposition, and each failed attempt is a silent no-op.

Details on action-translation#118 and action-translation#225.

What to do, once #118 is fixed

1. Seed the lecture — translate init -f learning_approximation.md, on the released engine, with the localisation rules on (so it matches the rest of the edition: font config, localised figure labels and code comments).
2. Add it to lectures/_toc.yml in the Bounded Rationality in Macroeconomics block, between olg_adaptive_money and exchange_rate_learning, matching the source order.
3. Revert the four intersphinx references from Point the learning_approximation references at the English edition #209 to plain local {doc} links and drop the （英文版）markers:

File	Line
lectures/bounded_rationality.md	151
lectures/genetic_classifier.md	49, 580, 590

4. Native review — it will be unreviewed machine output, like the other seeds in this edition.

Worth knowing

This lecture is the estate's cheapest deterministic reproducer for #118, so it has value beyond the coverage gap: it is the natural acceptance test for any fix, and is named as day-one corpus in the engine benchmark plan (PROJECT-PLAN-ENGINE-BENCHMARK.md in QuantEcon/project-translation, tracked at action-translation#227). Do not seed it opportunistically before the fix lands — a successful roll would remove the reproducer without fixing anything.