Fixes + stable gateway ids

api/proto/common/trace/v1/trace.proto

@@ -2,8 +2,12 @@ syntax = "proto3";
 package common.trace.v1;
 option go_package = "github.com/tech/sendico/pkg/proto/common/trace/v1;tracev1";
 
+// TraceContext carries cross-service request correlation identifiers.
 message TraceContext {
+  // request_ref is the unique identifier for this individual request.
   string request_ref     = 1;
+  // idempotency_key prevents duplicate processing of the same operation.
   string idempotency_key = 2;
+  // trace_ref groups related requests within a single logical flow.
   string trace_ref       = 3;
 }