Update main page impact stories

* Add the new LAMMPS highlight
* Drop the DoD/E4S highlight

Author: bernhold

_data/featured-stories.yml

@@ -1,6 +1,7 @@
 # Impact stories to feature on main page
 - /impacts/2025-01-warpx
 - /impacts/2025-01-wdmapp
-- /impacts/2025-01-dod-hpc
+- /impacts/2026-01-lammps
+# - /impacts/2025-01-dod-hpc
 # - /impacts/2025-01-sw-ecosystem-power
 # - /impacts/2024-12-pnetcdf