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: *)

src/main/resources/fabric.mod.json

@@ -0,0 +1,24 @@
+{
+  "schemaVersion": 1,
+  "id": "${mod_id}",
+  "version": "${version}",
+  "name": "영상재생모드",
+  "description": "Play arbitrary mp4 URLs on block surfaces in Minecraft (Fabric).",
+  "authors": [ "tkrmagid" ],
+  "contact": {
+    "homepage": "https://git.tkrmagid.kr/tkrmagid/mc_video_player_mod",
+    "sources": "https://git.tkrmagid.kr/tkrmagid/mc_video_player_mod"
+  },
+  "license": "MIT",
+  "environment": "*",
+  "entrypoints": {
+    "main": [ "com.ejclaw.videoplayer.VideoPlayerMod" ],
+    "client": [ "com.ejclaw.videoplayer.VideoPlayerClient" ]
+  },
+  "depends": {
+    "fabricloader": ">=0.16.0",
+    "fabric-api": "*",
+    "minecraft": ">=1.21.6",
+    "java": ">=21"
+  }
+}