feat: add event and slug proto

proto/slug.proto

@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+package slug;
+
+option go_package = "./gen";
+
+service Slug {
+  rpc ChangeSlug(ChangeSlugRequest) returns (ChangeSlugResponse);
+}
+
+message ChangeSlugRequest {
+  string old = 1;
+  string new = 2;
+}
+
+message ChangeSlugResponse {
+  bool success = 1;
+  string message = 2;
+}