fix(mods): drop rechiseled from server — wrong MC version

rechiseled-1.2.5-neoforge-mc1.21.11.jar targets Minecraft 1.21.11 /
NeoForge 21.11, not this server's 1.21.1 / 21.1.233. As `both` it crashed
the server at pre-load (FATAL ModLoader: requires minecraft 1.21.11). Mark
`client` to exclude it from server-mods so the server boots.

NOTE: the jar is still wrong-version for clients too (same gate) — it must
be removed from / replaced in the distribution to be usable at all.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mods-sides.json

@@ -120,7 +120,7 @@
   "moreoverlays-1.24.2-mc1.21.1-neoforge.jar": "client",
   "polymorph-neoforge-1.1.0+1.21.1.jar": "both",
   "ponderjs-neoforge-1.21.1-2.4.0.jar": "client",
-  "rechiseled-1.2.5-neoforge-mc1.21.11.jar": "both",
+  "rechiseled-1.2.5-neoforge-mc1.21.11.jar": "client",
   "resourcefullib-neoforge-1.21-3.0.12.jar": "both",
   "rhino-2101.2.7-build.85.jar": "both",
   "rightclickharvest-neoforge-4.6.1+1.21.1.jar": "both",