Clean up dead code, fix type errors, and add publish workflow

Remove unused _append_ops_call_method, fix _property_data_from_member
call signature, replace sys.version_info guard with hasattr check for
__buffer__ protocol, fix implicit string concatenations, add msgbus
overrides for 4.0-4.4, add conformance tests, and add publish script.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

overrides/4.0/bpy.msgbus.json

@@ -0,0 +1,12 @@
+{
+  "subscribe_rna": {
+    "params": {
+      "key": "bpy.types.Property | bpy.types.Struct | tuple[bpy.types.Struct, str] | object"
+    }
+  },
+  "publish_rna": {
+    "params": {
+      "key": "bpy.types.Property | bpy.types.Struct | tuple[bpy.types.Struct, str] | object"
+    }
+  }
+}