The component seeded its parameters with `computeUrlParams()`, which reads
`window.location`. Element Call is not the page any more, so what it found
there was the host's URL: no `widgetId`, therefore not a widget, therefore no
intent, therefore the standalone app's preset.
The visible symptom was the Element Call logo in the footer of a call embedded
in someone else's application, since `showLogo` follows `header ===
HeaderStyle.Standard`. The rest of that preset mattered more. A hosted call
defaulted to `perParticipantE2EE: false` and `confineToRoom: false` — so
unencrypted, and willing to take the user out of the room a host had put them
in — and a host could not correct either without naming every parameter
itself, nor even name `header`, since the enums were not exported.
So the intent presets move out of `computeUrlParams` into
`configurationForIntent`, and the component builds its parameters from an
intent plus the properties a host has no URL to supply. `intent` becomes a
prop, defaulting to joining an existing group call: the lobby first, confined
to the room, encrypted per participant, and no Element Call branding in
someone else's interface. A host that knows which button the user pressed
should say which.
One deliberate difference from the widget presets: the background defaults to
solid rather than the gradient, which is drawn by a `position: fixed`
pseudo-element and would escape the container to cover the host.
`UserIntent.Unknown` still means the standalone preset, so the app and widget
are unchanged — including a widget that names no intent, which has always been
given those defaults.