fix(moshscript): skip sleep during dry runs

[padsbanger]

Summary

• make sleep(ms) honor the moshscript dry-run contract
• narrate the intended delay instead of blocking
• add a regression test that verifies Atomics.wait is not called

This fixes the PRD 0004 R7 dry-run guarantee: previews now avoid the sleep side effect along with process and network effects.

Verification

• node --test test/commands.test.mjs (13/13 passed)
• npm test on Node 22 (135/135 passed)