Recover assisted thaw progress and target completion

RE-1008. Focused validation: cargo xtask test-group qvm-assist-progress. Machine report.

Twenty-four original-QVM cases execute staged f32 progress using34062368 and helper clock6328, then actual152386 on the target with helper meter mirroring. Negative/wrapped elapsed time, signed duration, fractional carry, precision and threshold completion are covered. Assisted completion orders score/recipient reset/event108/log and mirrors zero to the helper. Helper clock advances after the target child; ownership remains until later cancellation. Native nested effects remain captured or supplied.