A dropped connection no longer strands a customer's payment tag

Subi tags customers and orders to reflect state like a payment failure. If the request to update a tag never got a response from Shopify, for example because of a dropped connection, the tag update was previously treated as failed and not retried, so a customer could keep a "payment failure" tag even after successfully paying.

Tag writes are now retried automatically, in the same request, when the failure looks like the request itself never reached Shopify, rather than Shopify actively rejecting it. This applies to the tag-write path generally, so it covers the customer and order tags Subi manages as part of billing and recovery.

A persistent connection problem still results in a failed tag write after a couple of quick retries, the same as before; this change targets the specific case where the request was lost in transit, not every possible tag-write failure.