refactor: collapse duplicated canonicalize/non-canonicalize branches in TgsExchange::begin() #21
Description
Summary
TgsExchange::begin() (src/protocol/tgs_exchange.rs, lines 222–250) contains duplicated logic across the canonicalize and non-canonicalize branches. These should be collapsed to reduce repetition and improve maintainability.
Suggested Change
Extract shared logic into a helper or unify the two branches so that the canonicalize flag only gates the minimal differing behaviour.