Add link to new blog post on Calcite constant folding

Signed-off-by: Mihai Budiu <mbudiu@feldera.com>

Author: mihaibudiu

site/community/index.md

@@ -249,6 +249,7 @@ If you have something interesting to share with the community drop us an email o
 consider creating a pull request on GitHub. If you just finished a cool project using Calcite
 consider writing a short article about it for our [news section]({{ site.baseurl }}/news/index.html).
 
+* <a href="https://www.feldera.com/blog/constant-folding-in-calcite">Constant folding in Calcite</a> (Mihai Budiu, 2025)
 * <a href="https://github.com/JiajunBernoulli/calcite-notes">Calcite notes about runnable examples and concise documents</a> (Jiajun Xie, 2024)
 * <a href="https://www.feldera.com/blog/calcite-irs/">Calcite program representations</a> (Mihai Budiu, October 2023)
 * <a href="https://datalore.jetbrains.com/view/notebook/JYTVfn90xYSmv6U5f2NIQR">Building a new Calcite frontend (GraphQL)</a> (Gavin Ray, 2022)