feat(M1): Fabric scaffold for MC 1.21.6 with /videoStick

- video_player mod id, 영상재생모드 display name
- VideoAnchorBlock + VideoAnchorBlockEntity (placeholder)
- VideoStickItem
- /videoStick (+ /videostick alias) command gives the stick
- gradle 9.5.1 wrapper, fabric-loom 1.16.2, Java 21 toolchain
- works in both singleplayer and dedicated server (environment: *)

settings.gradle

@@ -0,0 +1,12 @@
+pluginManagement {
+    repositories {
+        maven {
+            name = 'Fabric'
+            url = 'https://maven.fabricmc.net/'
+        }
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+rootProject.name = 'video_player'