Compiler UI — automatic compilation
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The default auto-compile countdown is 12 seconds, controlled per project by
tools/Compiler-UI.json: lifecycle.autoCompileDelaySeconds (number, 0..3600).
0 disables automatic compilation. For example, set 5, 12, or 30 seconds.

The local PowerShell Compiler-UI.ps1 process owns the countdown using a
monotonic clock. The browser only renders remaining time as reported by
/api/status; automatic build launch is not dependent on JavaScript timers.

The countdown starts after the Compiler UI loads and calls POST /api/ready.
Compile starts immediately on manual click; Cancel disarms the countdown.
Closing while compiling cancels the build, finalizes logs, then exits.
Closing before compiling disarms the countdown and exits.
The countdown is one-shot per Compiler UI session and does not restart
after cancellation or a failed build.
