Scaffold the emote library with a Stonecutter Fabric mod and tester

- core/: Minecraft-independent animation model (Bone, BoneTransform with
  bend fields, Pose, Animation, AnimationPlayer) with JUnit tests.
- src/main: Fabric mod built for 1.21.4-1.21.11 with Stonecutter on
  Mojang mappings. Samples each player's pose into its render state and
  applies it at the end of HumanoidModel.setupAnim (armor follows too).
- src/testmod: dev-only tester with /emotes play|stop|info and a mixin
  audit on startup.
- Publishing to the saturnclientmc Gitea Maven registry as
  org.saturnclient:emotes-core and emotes-fabric:<v>+<mc>.

Loom is pinned to 1.17 because 1.18 needs a Java 25 JVM.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

core/build.gradle.kts

@@ -0,0 +1,38 @@
+plugins {
+    `java-library`
+    `maven-publish`
+}
+
+group = "org.saturnclient"
+version = rootProject.property("mod.version") as String
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation(platform("org.junit:junit-bom:5.13.4"))
+    testImplementation("org.junit.jupiter:junit-jupiter")
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+}
+
+java {
+    // Kept at 21 so it runs on every supported Minecraft version.
+    toolchain.languageVersion = JavaLanguageVersion.of(21)
+    withSourcesJar()
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+
+publishing {
+    publications {
+        create<MavenPublication>("maven") {
+            artifactId = "emotes-core"
+            from(components["java"])
+        }
+    }
+}
+
+apply(from = rootProject.file("gradle/gitea.gradle.kts"))