Radio: three calls a person makes, and four teammates who go #290

trevato/cs has a radio: three calls a person makes from the keyboard, and four teammates who actually go. This repository has none — git grep -i radio src is empty — and it is the one thing on the parent's side of #287 that changes how a round is played rather than how it is drawn.

The parent's shape, for reference rather than for copying: a call is bound like any other action, and it stands in front of the round's site roll for a few seconds before falling back to it, so the bots read one answer and a person can move it.

Here it lands in this repository's shape, not that one:

• the calls are actions in src/bind.ts, so the bindings table and the touch pads pick them up from the one list (src/client/binding.ts and the test that holds them together);
• the override belongs beside the round's plan, not inside src/client/bots.ts: src/plan/plan.ts decides the site, so the call goes in front of plan and expires;
• the sound goes through the engine's device like every other noise, and is heard by the side that called it;
• the bots' side of it is already there — they take a site from the plan, so a call only has to change what the plan says.

Done when: a bound key makes the call, the HUD says what was called and by whom, the bots on that side go, the call expires back to the roll, and a seeded round with a call in it is pinned by a digest the way the rest of the round is.