--fix-moved leaves the generated explainer pages and llms-full.txt stale #1272

Where: scripts/check_external_links.py (fix_moved), scripts/build_explainers.py.

Current gap: After a link in explainers/*.md is rewritten, the generated HTML pages, assets/explainers-data.json and llms-full.txt still carry the old address until make build-explainers is run by hand, and the generated-files check fails in between.

Suggested approach: Offer --fix-moved --rebuild that runs the explainer build when an explainer changed, or print the exact command with the list of changed files.

Done when: after --fix-moved --rebuild the generated-files check passes, covered by a test with a stubbed builder.