PHLEGM v8 - Revision r94 - compiler ETA overrun prediction

When the running build's known-duration countdown reaches 00:00.000, the
'Predicted build' duration begins counting UP from its original estimate.

Before estimate expires:
  Predicted build (avg 5/7 of 7 good): 02:00.000 · ETA: 00:30.000

At estimate expiry:
  Predicted build (avg 5/7 of 7 good): 02:00.000 · ETA: 00:00.000

After estimate expires:
  Predicted build (avg 5/7 of 7 good): 02:01.250 · ETA: 00:00.000 · Overrun: +00:01.250

Only the displayed prediction grows during an overrun. The original prediction
basis stays immutable for that build; progress continues its existing capped
non-linear overrun curve; persisted rolling duration history changes only on a
completed successful build. A failed/cancelled build does not update history.

Unknown-duration builds continue to show elapsed time. The next-build forecast
shown while idle continues to use the original successful-build rolling average.
Successful/failed/cancelled build status shows actual elapsed time at finish.

The GUI uses one shared formatter for initial/status-refresh rendering and
animation frames to avoid flicker or a reset every 500 ms. The behavior is
shared/data-driven and does not introduce project-specific compiler logic.

Verification: Node.js isolated production JavaScript runtime tests cover
countdown, exact zero, +1 ms, +1.250 s, long overruns, missing start time,
and zero/invalid basis. ZIP integrity and CRLF/LF policy are checked.
Native PowerShell/UI runtime tests are not available on this build host.
