Documents the bridge with a card-authorization state chart end to end:
the SCXML, the setup call, the four macrostep spans the run exports,
the span events on each, and the invoke handler a host registers for
"myapp:authorize". A shorter signup-wizard A/B section carries the
cardinality point - a variant lands in statifier.event_name and
statifier.configuration, never in the span name.

Every snippet is executed by a new end-to-end test rather than
asserted by eye. It is the first test here to drive the bridge through
a real Statifier.Session instead of hand-emitted telemetry, which is
what makes the documented span shapes verifiable at all.

Also refreshes the status paragraph, which still called the package an
early implementation after 0.1.1 shipped.

Refs: ots-o3i