feat: Add VRM Blender addon with complete import/export functionality

- Add core VRM addon infrastructure with manifest and registration
- Add common utilities module with file system, logging, and conversion helpers
- Add human bone mapper with support for multiple rigging standards (Mixamo, MMD, Unreal, Rigify, etc.)
- Add VRM 0.x and 1.x format support with property groups and handlers
- Add editor UI panels for VRM metadata, spring bones, and MToon materials
- Add exporter with glTF2 extension support for VRM format serialization
- Add importer with scene reconstruction and armature generation
- Add MToon shader support with auto-setup and material migration
- Add spring bone physics simulation with constraint handling
- Add node constraint editor for advanced rigging control
- Add comprehensive validation and error handling with user dialogs
- Add scene watcher for real-time property synchronization
- Add workspace management and preference system
- Include Python cache files and Blender manifest configuration
- This is the initial commit establishing the complete VRM addon ecosystem for Blender

common/test_helper.py

@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: MIT OR GPL-3.0-or-later
+from typing import Optional
+from unittest import TestCase
+
+import bpy
+
+from .blender_manifest import BlenderManifest
+
+DEVELOPMENT_MODULE = ".".join(__name__.split(".")[:-2])
+MANIFEST_ID = BlenderManifest.read().id
+
+
+def make_test_method_name(text: str) -> str:
+    replaced_chars: list[str] = []
+    for char in text:
+        if char == "«":
+            replaced_chars.append("««")
+        elif char == "»":
+            replaced_chars.append("»»")
+        elif ("_" + char).isidentifier():
+            replaced_chars.append(char)
+        else:
+            replaced_chars.append(f"«{ord(char):x}»")
+    return "test_" + ("".join(replaced_chars))
+
+
+class AddonTestCase(TestCase):
+    disabled_installed_module: Optional[str]
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        super().setUpClass()
+
+        cls.disabled_installed_module = None
+        for addon in bpy.context.preferences.addons:
+            module = addon.module
+            if not module.endswith("." + MANIFEST_ID):
+                continue
+            bpy.ops.preferences.addon_disable(module=module)
+            cls.disabled_installed_module = module
+
+    def setUp(self) -> None:
+        super().setUp()
+        bpy.ops.preferences.addon_enable(module=DEVELOPMENT_MODULE)
+        bpy.ops.wm.read_homefile(use_empty=True)
+
+    def tearDown(self) -> None:
+        super().tearDown()
+        bpy.ops.preferences.addon_disable(module=DEVELOPMENT_MODULE)
+
+    @classmethod
+    def tearDownClass(cls) -> None:
+        super().tearDownClass()
+
+        disabled_installed_module = cls.disabled_installed_module
+        if disabled_installed_module is not None:
+            bpy.ops.preferences.addon_enable(module=disabled_installed_module)
+
+        cls.disabled_installed_module = None