prompt: file the multi_dataset/jax_likelihood XLA compile stall

multi_dataset/jax_likelihood/mge.py was parked out of the PR smoke gate
(autolens_workspace_test#262) to unblock the pynufft removal, after hanging
to the 300s cap in 4/4 jobs on a PR whose diff that gate never executes.

Parking removes the symptom, so this prompt is what keeps the cause visible.
It is not a new bug: no_run.yaml already records the sibling delaunay.py as
an "intermittent XLA compile stall, family-wide" (autolens_workspace_test#245),
and mge.py's signature matches exactly — 32s when it passes, otherwise no
progress at all.

The real cost is the accumulation: the whole multi_dataset/jax_likelihood
family is now quarantined somewhere, three times over, without anyone having
diagnosed the stall. The prompt asks for the stall to be characterised rather
than the scripts sped up, and for the runner to leave a stack trace on
timeout — today a hang produces no evidence, which is why it keeps recurring.

Author: claude