Carry IndexedDbName through factories, backend state, request queues and
connection notifications so unpaired surrogates stay distinct from U+FFFD.
Preserve the legacy JSON map for Unicode names and persist other names as
UTF-16 code units alongside it.
Cover records, versions, rollback, deletion, cross-realm calls and worker
notifications with a shared browser fixture, plus persistence and queue tests.
Validation: cargo fmt --all; strict workspace clippy; cargo nextest run
--no-fail-fast (19209 passed, 13 skipped).