PUSH-01: appPath now rejects a path that resolves to a leading // after
the URL parser handles dot segments (also %2e), backslashes and stripped
tabs and newlines, and planClick throws if the final URL is off origin.
Regression tests drive openNotification with the attack forms.
PUSH-02: subscribePush no longer asks for notification permission where
navigator.userActivation is unavailable; it throws a typed
PermissionGestureError ('unobservable', or 'inactive' outside a tap).
The test for that path now overrides userActivation directly: the old one
passed undefined into a defaulted parameter and so never exercised it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>