/live closes any text frame over 4096 bytes with 1009 - the three-line cap plus its boundary tests #188

Replaces #123, which a builder left without a pull. The code is three lines in Software/so101/src/lobby.ts, already on pull #25's branch (smith/20-public-launch-check-a-stranger-watches-s, 16722ff). This issue adds only the tests that pull never got.

Done:

• [ ] Before parsing, lobby.ts counts each /live message's bytes with frameBytes (src/frame-limit.ts) and closes with 1009 over 4096 bytes.
• [ ] In src/lobby.test.ts: 4096 ASCII bytes are handled and the socket stays open; 4097 bytes close with 1009; 1366 three-byte characters (4098 bytes) close with 1009.
• [ ] forge.json untouched. bun --cwd Software/so101 test and bun x tsc --noEmit pass.