`long` is a reserved word in the Qt 6.7 QML parser the CI (KDE neon)
uses, so tst_provider_normalizer.qml failed to compile there and
`make check` stayed red even though a newer local Qt accepted it.
Rename the local to `oversized`.

Also document the truncate-before-sort order in normalizeSessions,
which the review asked to call out for future CLI payload changes.