Bun's `process.title` setter is a JS-level no-op: it stores the value
internally but never calls `prctl(PR_SET_NAME)`, so `omp` appeared as
`bun` in ps/pgrep/killall/top and `pkill bun` became a footgun killing
every Bun process. Add `setProcessName` in pi-utils that also drives
prctl via bun:ffi on Linux, and use it at CLI startup and in the daemon
broker.
Fixes#6815
roboomp