A moderator's ban over /live is refused with 'that address is yours too' when the target shares the moderator's address, proven through the socket #344

Replaces #209. Pull #334 failed review three times because only the owner can ban today, and the owner is never barred, so the guard had no path to fire. This lands after #227 gives moderators ban.

Done:

• [ ] In Software/so101/src/lobby.ts, inside the moderator's ban path from #227, a ban whose target address (live seat, or Accounts.addressOf when offline) equals the moderator's own is refused with "that address is yours too: the ban would bar you", and nothing changes. The guard and Accounts.addressOf may be taken from pull #334's branch.
• [ ] src/lobby.test.ts proves it through the socket: a moderator and a user on the same address, the moderator sends ban, gets the error, and both stay in. The test fails if the guard line is deleted. A moderator banning someone on another address still works.
• [ ] README's moderation paragraph mentions the refusal. forge.json is untouched. After bun install, bun x tsc --noEmit and bun --cwd Software/so101 test pass.