Add pre-commit hook to auto-sync News/homepage/bot pages

Versioned hook at tools/git-hooks/pre-commit runs build_listings.py and
build_botlinks.py on every commit and stages their output, so the News hub,
homepage "Latest news", /llms.txt and /links-for-bots/ always reflect the actual
Blog/Projects/News content — no manual step. Non-blocking: warns and proceeds if
Python or a generator fails. Activated with `git config core.hooksPath tools/git-hooks`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/git-hooks/README.md

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+# Git hooks
+
+Versioned hooks that keep auto-generated files in sync.
+
+## Activate (once per clone)
+
+```sh
+git config core.hooksPath tools/git-hooks
+```
+
+That points git at this folder. From then on, every `git commit` runs
+`tools/build_listings.py` and `tools/build_botlinks.py` and stages their output,
+so the News hub, homepage "Latest news", `/llms.txt` and `/links-for-bots/` stay
+in sync with the actual Blog / Projects / News pages.
+
+The hook never blocks a commit — if Python or a generator fails it just prints a
+warning and lets the commit proceed.
+
+> Note: SEO metadata and the sitemap are **not** regenerated on commit (that is a
+> heavier, all-pages pass). When you add a new page, also add its date to
+> `ARTICLE_DATES` in `tools/seo_inject.py` and run
+> `python tools/seo_inject.py --all --sitemap`.