feat: 添加VRM网格工具插件，支持网格分离和UV边融并功能

添加VRM网格工具插件，包含以下主要功能：
- Body网格分离：将非皮肤材质面分离为独立对象
- UV边融并：根据预定义UV数据将三角面转换为四边面
- 提供独立面板和操作符，与VRM官方插件兼容
- 包含材质处理顺序和自动转换逻辑
- 添加JSON数据文件和工具函数

__init__.py

@@ -0,0 +1,45 @@
+# SPDX-License-Identifier: MIT
+# VRM Mesh Tools - Standalone mesh separation and UV edge merging tools
+
+bl_info = {
+    "name": "VRM Mesh Tools",
+    "author": "VRM Mesh Tools Contributors",
+    "version": (1, 0, 0),
+    "blender": (4, 2, 0),
+    "location": "View3D > Sidebar > VRM Tools",
+    "description": "Standalone mesh separation and UV edge merging tools for VRM models",
+    "warning": "",
+    "support": "COMMUNITY",
+    "category": "Mesh",
+}
+
+from .ops import (
+    VRM_TOOLS_OT_separate_non_skin_faces,
+    VRM_TOOLS_OT_merge_uv_edges,
+)
+from .panel import (
+    VRM_TOOLS_PT_mesh_separator,
+)
+
+# Classes to register
+_classes: list[type] = [
+    VRM_TOOLS_OT_separate_non_skin_faces,
+    VRM_TOOLS_OT_merge_uv_edges,
+    VRM_TOOLS_PT_mesh_separator,
+]
+
+
+def register() -> None:
+    """Register all classes for the addon."""
+    import bpy
+
+    for cls in _classes:
+        bpy.utils.register_class(cls)
+
+
+def unregister() -> None:
+    """Unregister all classes for the addon."""
+    import bpy
+
+    for cls in reversed(_classes):
+        bpy.utils.unregister_class(cls)