/live answers {type:'who'} with who is here: usernames, guest names with their colour, and driving, queued or watching - lobby and test only #363

Rewritten from #292, piece 2 of 3.

Done:

• [ ] On {type:'who'} the lobby answers that socket alone with {type:'who', people:[{name, colour?, guest:boolean, role:'driving'|'queued'|'watching'}]}. A signed-in person with two tabs is listed once. At most one request per second per socket is answered.
• [ ] No address, user agent or user id is in the frame.
• [ ] Tests: the driver is marked driving, a queued user is queued, a guest has its colour, and a second request within a second is not answered.
• [ ] forge.json untouched, and bun --cwd Software/so101 test passes.

Replaced by #371: the same work, without the blocker on #291 (closed as split) that this one inherited and that kept it parked. Dropping this one.

Unstick note: this is parked only because it inherited the edge to #291, which was closed as split into #358 and #359. #358 is on main (97ab64b), and #359 is being built. The work as written still stands, and its real blockers are already named, so nothing about it needs to change. Planner edits cannot lift a park, so a person needs to clear it. Once that is done, #362 is ready now, and #363, #364 and #366 follow their named blockers.

Re-planned as #397. Same scope. #397 waits only on #396, not on the split #291.