Include the common mod resources in the subprojects.

build.gradle.kts

@@ -27,6 +27,16 @@ subprojects {
         mixinConfig("snowygui-mixins.json")
         refmapName = "snowygui-common-refmap.json"
     }
+    this.sourceSets {
+        main {
+            resources {
+                val commonRes = project(":common").sourceSets.main.get().resources
+                if (!this.srcDirs.containsAll(commonRes.srcDirs)) {
+                    srcDir(commonRes.srcDirs)
+                }
+            }
+        }
+    }
     dependencies {
         shadowC(kotlin("stdlib-jdk8"))
         "minecraft"("com.mojang:minecraft:${rootProject.property("minecraft")}")