fix(lockfile): scope exit hooks to owned locks

[AmanVarshney01]

Problem

Importing @alchemy.run/node-utils/lockfile registers SIGINT and SIGTERM handlers even when no lock is owned. Alchemy imports this module transitively from alchemy/Output, so those handlers can call process.exit() before a host finishes graceful shutdown.

Fix

• Register one cleanup hook when the first lock is acquired
• Keep it through concurrent locks and async release
• Remove it after the final lock is released or compromised

Testing

• bun run build
• bun test (77 passed)