W89 does not appear on front page

There is one conference (NODALIA 1989) in W89.xml, but no workshop page is generated for 1989 on the front page of the antology. The individual pages are accessible though, see e.g., [W89-0101](https://www.aclweb.org/anthology/papers/W/W89/W89-0101/).

Start by inspecting W89.xml and the entry point that builds the Anthology front page, then compare its handling with nearby workshop years. Verify why NODALIA 1989 is omitted while W89-0101 remains accessible, and consider the issue done when the 1989 workshop appears on the front page without breaking the existing individual-page link.

索引モデルが issue の本文から書いたものです。