A moderator can ban and unban over /live, never the owner or another moderator, and receives the banned list #227

Split from #190 (part of #13). This builds on the moderator gate from the delete piece.

Done:

• [ ] In Software/so101/src/lobby.ts, a verified moderator may send ban with on true or false. Each ban or unban is logged with who did it.
• [ ] A moderator who bans the owner or another moderator gets an error, and nothing changes.
• [ ] Moderators receive banned on join and on every change, as owners do today.
• [ ] Tests in src/lobby.test.ts: a moderator bans a user and the user is barred, a moderator is refused against the owner and against another moderator, and a plain user is refused.
• [ ] forge.json is untouched. bun --cwd Software/so101 test passes, and the preview deploys.