vgsp: kick-lane + client-VAS ring resolution upgrades (CONT.421-423)

- kick latch: keep an adopted-but-unconfirmed kick-family USERD latch
  across a transient put=0 (sema_kick_latch_keep, default 1) - the
  r1771 ADOPT->REJECT sequence dropped the block 7 s after adoption and
  left the GL/kick lane dark.
- service-thread starvation: budget the VAS-PROMOTE walk log and back
  the promote sweep off 250 ms after a failed pass
  (sema_vas_promote_backoff, default 1); both brought ~100 pr_info/s
  down to <1/s during GZDoom's GL init stall; also budget the RING-VAS
  mapped print.
- direct-GL client ring: always-probe the beef-family channels against
  the parked VAS candidates (sema_vas_client_ring, default 1,
  rate-limited per channel) with per-channel failure backoff, a
  smallest-unused-rank fallback (rank collision had disabled the
  content-scan backup) and oldest-same-VAS park eviction for the
  client's VAS churn. Live receipts: ring mapped, GR latch confirmed,
  push count 20->157, releases applied per frame (values 0x1->0x20),
  X channel-idle timeouts 0 during GL bursts.
- Validation: glxgears 469-522 FPS (no regression); GZDoom now completes
  GL init and reaches screen allocation with the client lane live
  (~120 s) instead of dying seconds after V_Init.

0 files changed, 0 insertions, 0 deletions