fix(mods): mark cwb (Cubes Without Borders) client — crashes dedicated server

cwb declares @Mod(dist=CLIENT); classify-mods.py read its toml side as
BOTH (the dist annotation isn't in the manifest), so it synced to the
server and RuntimeDistCleaner FATAL'd on CubesWithoutBordersImpl. Flip
to client so sync drops it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mods-sides.json

@@ -63,7 +63,7 @@
   "createtransmission-1.2.1+neoforge-create6-1.21.1.jar": "both",
   "createultimine-1.21.1-neoforge-1.3.2.jar": "both",
   "curios-neoforge-9.5.1+1.21.1.jar": "both",
-  "cwb-neoforge-3.0.0+mc1.21.jar": "both",
+  "cwb-neoforge-3.0.0+mc1.21.jar": "client",
   "defaultoptions-neoforge-1.21.1-21.1.6.jar": "both",
   "drippyloadingscreen_neoforge_3.1.2_MC_1.21.1.jar": "client",
   "easy-piglins-neoforge-1.21.1-1.1.0.jar": "both",