prepare for refactor

buf.gen.yaml

@@ -0,0 +1,16 @@
+version: v2
+clean: true
+managed:
+  enabled: true
+  override:
+    - file_option: go_package_prefix
+      value: github.com/mizuchilabs/mantrae/proto/gen
+plugins:
+  - local: protoc-gen-go
+    out: proto/gen
+    opt: paths=source_relative
+  - local: protoc-gen-connect-go
+    out: proto/gen
+    opt: paths=source_relative
+inputs:
+  - directory: proto