configure_logging() now runs with default arguments when kanta.logging
is imported, attaching a plain stderr handler with propagate=False to
the event loggers (kanta.bootstrap/migration/transaction) that carry
Kanta-rendered output. No levels are set by default, so event output
inherits the effective root level: a framework switching root between
INFO in development and WARNING in production governs Kanta output too.
Other configure_logging changes: channel enable flags use
logger.disabled (propagate toggling no longer silences now that event
loggers have their own handler), skiproot=False removes Kanta's
handler and re-enables propagation so the root logger renders event
output, and debug=True lifts only the DEBUG-emitting loggers
(bootstrap, migration) to DEBUG instead of setting a level on the
"kanta" parent.