The daemon supervisor tests (22, 23, 25) spawned the supervisor through
`npx tsx` which creates a wrapper process. When SIGINT was sent, the npx
wrapper died with signal=SIGINT instead of forwarding it to the actual
supervisor which handles graceful shutdown. Now matches production startup
pattern using process.execPath with --import tsx.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>