feat: give group participants room, search and copy

[Alaraajavamma]

A participant card put the name, the number and three buttons in one
row, so the name was capped at fifteen characters to make space. The
text gets the full width now and the buttons sit under it, which also
makes room for two actions the call details already had and the group
sheet did not: searching the sender online and copying the number.
Both work for alphanumeric senders too, where searching is at its most
useful and calling is impossible. The card carries no margins of its
own, because the app's card style already pads twelve pixels and every
margin added here stacked on top of it.

The search buttons made the settings dishonest, so they are split by
what they govern. The switch that claimed to control the search button
in the in-call window and call history only ever controlled the
in-call one, and it hid the engine choice with it, leaving the engine
unreachable from the surfaces that used it regardless of the switch.
The engine moved to its own Number Lookup category, visible from the
calls and the messages app alike, because the buttons it serves are in
both while the screening options remain call things. Buttons inside
menus the user opens are not gated at all: a feature behind a switch
is a feature nobody finds, and the in-call button keeps its opt-in
because it is the one that appears uninvited.

The participants panel and the search bar slide in from the chat
header rather than floating over the list, so nothing dismissed them;
a tap in the conversation now does, left unclaimed so it still does
whatever it was aimed at. A search with text in it stays, since
tapping the filtered list is how a result is reached.