* test(settings): replace covered notification/diagnostic greps with executed tests

The quota, command-construction, timeout and tooltip wiring of
configNotifications.qml and configDiagnostics.qml is now exercised by
seven tests in tst_settings_pages.qml that instantiate the real pages:
the master switch owns its toggles, the predictive tooltip keeps its
plainText routing, runDiagnostic issues the redacted nonce command for
a blank provider, the output area follows accepted output, the timeout
timer retires hung commands, a command-path change retires the active
command, and accepted output stays bounded while stale replies are
ignored.

Each removed fragment was verified by breaking the behavior it
describes and confirming an executed test goes red; literal English
text stays green by design (owned by the i18n catalog) while the
wiring mutation behind it goes red. No production code changes.

* test(checks): drop unused page variables after assertion removal

The last NOTIFICATIONS_QML and DIAGNOSTICS_QML uses left with the
removed assertions, tripping SC2034 in check-shellcheck.