fix(cli): fail fast on hanging keychain commands

[brendanjryan]

Context

Attempt to address hanging tests on prs / main

Summary

• add bounded timeouts for CLI keychain subprocesses
• kill hanging Linux secret-tool store calls instead of waiting forever
• harden runtime test server teardown so HTTP helpers aggressively close sockets and avoid lingering keep-alive state
• make the keychain timeout configurable with MPPX_KEYCHAIN_COMMAND_TIMEOUT_MS

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/mppx@272

commit: 9b67c04