feat: update frames schema

proto/message_contents/frames.proto

@@ -12,8 +12,12 @@ option java_package = "org.xmtp.proto.message.contents";
 // The message that will be signed by the Client and returned inside the
 // `action_body` field of the FrameAction message
 message FrameActionBody {
+  // The URL of the frame that was clicked
+  // May be different from `post_url`
   string frame_url = 1;
+  // The 1-indexed button that was clicked
   string button_index = 2;
+  // Timestamp of the click in nanoseconds
   uint64 timestamp_ns = 3;
   // A unique identifier for the conversation, not tied to anything on the
   // network. Will not match the topic or conversation_id