vgsp: fail4 - cure the stale-wedge republish loop; enable staging snapshots for the sw-copy client

Two fixes, both demanded by live evidence:

1) Stale-wedge republish loop (r311-r312): the pump's per-channel write-back
did not persist gr_pub_armed, so the residual watchdog re-armed every pass;
its recovery kept zeroing the completion word and re-publishing (pub-adv/
zero/stale-wedge 3s cycles, exit: pub-adv pa=... val=104 cur=0 last=0). The
word oscillated under a live client that then never completed (r311 vector_add
wedged; guest sshd died). Persist gr_pub_armed/counter_gen in the write-back
and keep them (plus slot_pend_tries) across same-generation re-registration.
Also guard the residue zero: never zero a completion word authored by the
live session generation (r312 instrumentation: pub-adv-wrc + stale-recover-
zero + skip witness). Verified r313: stale-wedge rows 0 (was 66+), client
completes, guest survives.

2) Staging snapshot capture for the sw-copy client (r311): the decode-time
H2D capture gate required src_aperture == CE_APERTURE_SYS, but the driver
sends no SET_SRC_PHYS_MODE for the 1MB chunk copies, so src_ap defaulted to
VID and the gate never matched - zero captures on every run r302-r310 while
executions read the (driver-refilled) staging late. Gate judge is now the
translation: capture when the first source page resolves through SYS. First
verified captures (r311: 2-3 per run, real client bytes in first4) - partial
coverage only; the remaining pipeline-order gap is the open lead (see
handoff CONT.57).

Diagnostics kept: snapgate witness, pub-adv-wrc, stale-recover-zero[-skip].

0 files changed, 0 insertions, 0 deletions