Recover assistance acquisition and target ownership

RE-1004. Focused validation: cargo xtask test-group qvm-assist-acquire. Machine report.

Thirty-six original-QVM cases recover assistance acquisition after near/protected-target routing. A helper already holding mask8192 and nonzero active6316 cannot switch away from a different target6320. Otherwise acquisition sets mask8192, active1, target and clock6328, then requests event104 with target entity word0 followed by the source thaw-start log. Raw high bits and wrapped tick values survive; event/log bodies and preceding distance/admission gates are excluded.