[arzafran]

What this does

Adds a small dev script that measures how much CPU, how many wakeups and how much memory a running terminal app uses while it sits idle. Run it against Programa, Ghostty or any other terminal on the same machine to get numbers that can be compared directly.

First run on the Release build: 540 to 600 ms of idle CPU per 30 s window, 223 MiB resident, 260 MB physical footprint.

Summary

• New file scripts/measure-idle.sh, nothing else changes. Takes a PID or an app executable name, plus optional window length (default 30 s) and run count (default 3).
• CPU comes from ps time deltas, wakeups from top, memory from ps RSS and footprint.
• Exits non-zero with a message when the name matches zero or several processes.

Test Plan

• bash -n scripts/measure-idle.sh prints nothing and exits 0 (done).
• Ran against the Release app by name: prints the table and the memory line (done).
• Unknown app name: exits 1 with "expected one running ... found 0" (done).
• PID argument: measures that process (done).
• Not run: the app test suites, since no app code changed.

Linear: INC-452

Fixes INC-452