llms.txt and llms-full.txt do not cover TBV and serve placeholder content

Split out of a Greptile thread on #463, where the site footer gained links to `/llms.txt` and `/llms-full.txt`.

The links are not broken. Both are served in production:

```
https://docs.babylonlabs.io/llms.txt -> 200, text/plain, 4527 bytes
https://docs.babylonlabs.io/llms-full.txt -> 200, text/plain, 3388 bytes
```

The content is the problem.

- `llms.txt` describes only the Bitcoin staking protocol and is stamped `Version: 1.4.0`. It does not mention Trustless Bitcoin Vaults at all.
- `llms-full.txt` is largely placeholder text — its first section body reads "Placeholder content fo...".

So an agent that follows either link gets a stale or empty picture of the docs, and now gets there from a visible footer link rather than by guessing the URL.

Worth noting for whoever picks this up: neither file is committed to this repo, and no Docusaurus plugin here generates them. The registered plugins are only `fetch-remote-docs.cjs`, `tailwind-plugin.cjs`, and `webpack-react-provider.cjs`. The files are placed by the deploy pipeline, so the fix likely belongs there or in a new generator in this repo.

Suggested outcome: generate both files from the current docs tree at build time, so they stay in step with the content and pick up the TBV collection.

Start by inspecting the deploy pipeline and the current docs tree, since llms.txt and llms-full.txt are not committed and are placed during deployment. Review the registered fetch-remote-docs.cjs, tailwind-plugin.cjs, and webpack-react-provider.cjs plugins before deciding where generation belongs. Done means both production files are generated from current documentation, include the TBV collection, and contain no placeholder content.

Written by the indexing model from the issue text.