bench/launch-check.ts checks a deployed URL as an anonymous visitor and prints PASS/FAIL per item - against today's main #145

Replaces #125, without its wait on #120 (/healthz) and #123 (the /live cap). Main's health is already / (044b88b), and #123 carries its own tests, so this piece needs neither.

Done:

• [ ] bun run Software/so101/bench/launch-check.ts <url> checks, without signing in: / answers 200, is server-rendered and carries Content-Security-Policy, X-Content-Type-Options and Referrer-Policy; /status answers (200, or 503 with a reason while the arm reconnects); /live opens and pushes a status message within 2 s; anonymous POSTs to /move, /torque and /stop are refused; a forged x-forge-identity header does not sign anyone in.
• [ ] It prints one PASS/FAIL line per item and exits non-zero on any FAIL. It never sends a command that could move the arm, other than the refused ones above.
• [ ] bench/launch-check.test.ts runs it against a local relay on the simulated arm and expects every item to PASS.
• [ ] The README says how to run it against production and against a preview.
• [ ] bun --cwd Software/so101 test and bun x tsc --noEmit pass.