New content not reflected immediately in the `/llms.txt` or `llms-full.txt`

Bug description

We are using the GitBook SaaS platform and when we add a new page via the GitBook UI we notice that new content is not reflected in either /llms.txt and /llms-full.txt. We these endpoints to be dynamic (not static or cached) and reflect the content as it updated. This is really important for our customer facing support features.

How to reproduce

1. Add a new page
2. Check /llms.txt
3. You will notice the new page is not referenced in llms.txt

Additional context

Relevant code - https://github.com/GitbookIO/gitbook/blob/main/packages/gitbook/src/app/sites/static/%5Bmode%5D/%5BsiteURL%5D/%5BsiteData%5D/llms.txt/route.ts

Notice the export const dynamic = 'force-static';

Start with packages/gitbook/src/app/sites/static/[mode]/[siteURL]/[siteData]/llms.txt/route.ts, especially its force-static setting and how site content is loaded. Reproduce the issue by adding a page in GitBook and checking both /llms.txt and /llms-full.txt. Done means newly added content appears in both endpoints without waiting for stale output.