_Transaction.__aenter__ acquired a connection then called tx.start(); if start() raised
(stale pooled conn after failover/idle-timeout — a fail-loud path), __aexit__ never ran so
the connection leaked, draining the pool until transaction() deadlocked on acquire(). now
release-on-failure. verified: 6 forced start-failures (2x pool) no longer exhaust the pool.
bump v0.1.0 -> v0.1.1
Signed-off-by: disqualifier <dev@disqualifier.me>
dsql