mason: preserve giant rust cold-start passes

Give completed transform page series a 30-second cold execute deadline while keeping page uploads at five seconds, and fail execute deadlines without reconnecting or restarting the series.

Preserve over-budget native delta cores after evicting other sessions, with honest over-budget telemetry. The former oversized-snapshot refusal test now asserts this intentional preservation contract.

Co-Authored-By: Alfonso <alfonso@cortexkit.io>