fix(docs): correct publish_dir for Astro Starlight deploy (#904)

## Summary
- Fixed the `publish_dir` in the docs workflow from `docs/dist/any-llm`
to `docs/dist`
- Astro's `base` config only affects URL prefixing, not the build output
directory, so the deploy was copying from a non-existent path and
pushing an empty site to gh-pages

## Test plan
- [ ] Merge to main and verify the docs workflow deploys HTML to
gh-pages
- [ ] Confirm https://mozilla-ai.github.io/any-llm/ loads correctly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: njbrake

.github/workflows/docs.yaml

@@ -78,4 +78,4 @@ jobs:
         uses: peaceiris/actions-gh-pages@v4
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
-          publish_dir: docs/dist/any-llm
+          publish_dir: docs/dist