Add proxy layer to auth and sign and get initial data apis

PiperOrigin-RevId: 575867816
diff --git a/build/source_list.bzl b/build/source_list.bzl
index 3fae501..a766578 100644
--- a/build/source_list.bzl
+++ b/build/source_list.bzl
@@ -1605,6 +1605,7 @@
     "blind_sign_auth/proto/blind_sign_auth_options.proto",
     "blind_sign_auth/proto/get_initial_data.proto",
     "blind_sign_auth/proto/key_services.proto",
+    "blind_sign_auth/proto/proxy_layer.proto",
     "blind_sign_auth/proto/public_metadata.proto",
     "blind_sign_auth/proto/spend_token_data.proto",
 ]