A property named `on<Upper>` is filed as a signal handler as soon as a
sibling member `<upper>` exists: its initializer never binds, it sits at
the type default, and nothing warns. `PurchasesView.qml` declared
`onAlbums` next to `albums`, so the Albums tab bound `[]` once and never
re-evaluated, which blanked Purchases for every account with real
purchases. Reproduced standalone with the `qml` runtime: the identical
expression under another name reads `true`.
Rename it to `albumsTab` and the four other `on<Upper>` properties
(`collectionsTab`, `surfaceTint`, `accentFloor`, `litColor`) so the rule
can be exact, and add `qml_on_prefixed_property_audit.py` to the four
QML audit sites (qt-run, cargo-test, test-crates, qt-gate-windows).
cc
vicrodh
1cb988954e