Can we capture the PublishTransaction TCM URI in custom Resolver while publishing?
It's not possible. The resolver doesn't know/care about the concept of Publish Transactions. To elaborate on this, the method signature
Resolve has 4 parameters, none of which you can use to somehow trace back the ID you are searching for. Also, take the following scenario for example, when in the Publish dialog you click
Show items to publish the resolver gets triggered, but there is no Publish Transaction yet because a Publish action is not yet saved. The Id is assigned upon saving.