fix(client/net): split the receipt stamp from the pull + bleed standing latency

The two-pair investigation (wired Mac clients stuck at a rock-steady
~18-19 ms "network" that survived the load ending and cleared only on
reconnect) exposed two structural gaps, one of measurement and one of
recovery:

- Receipt was stamped at the hand-off PULL (Swift nextAU, pf-client-core,
  Android decode loops), not at reassembly completion — so any client-side
  standing state between the reassembler and the pull read as NETWORK
  latency, undiagnosable from the HUD. ABI v9: `PunktfunkFrame`/`Frame`
  grow `received_ns`, stamped by `Session::poll_frame` as the AU crosses
  the session boundary. Every embedder now uses the core stamp; the Apple
  client keeps the pull instant as `AccessUnit.pulledNs` and shows the
  receipt→pull wait as its own "client queue" term (detailed HUD tier from
  2 ms + a `queue_p50` stats-log field). Decode stages keep their pull
  anchor on all platforms, so no historical stage shifts meaning.

- The jump-to-live detectors deliberately ignore anything under 6 queued
  frames / 400 ms behind — so a small, constant, loss-free elevation (a
  sub-frame standing backlog, or a stale clock offset after a wall-clock
  step/slew) is carried for the rest of the session. New third detector
  (`StandingLatency`, unit-tested ladder): window-MIN one-way delay
  ≥ 10 ms above the session floor with zero loss for ~4.5 s escalates
  gently — a free clock re-sync first (an applied re-sync re-bases the
  floor), then at most 3 flush+keyframe bleeds sharing the jump-to-live
  cooldown, then a loud disarm naming what it means. Loss windows reset
  the run: congestion belongs to FEC/ABR, not this detector.

Also: mid-stream re-sync apply/discard logs debug→info — they are the
forensic trail for the stale-offset case and were invisible in the field.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/android/native/src/decode/sync_loop.rs

@@ -221,7 +221,13 @@ pub(super) fn run_sync(
                     // samplers (`received` point, host/network split) stay gated on the overlay so
                     // the hidden steady state adds only a wall-clock read + the receipt push.
                     if stats.enabled() || measure_decode {
-                        let received_ns = now_realtime_ns();
+                        // Core reassembly-completion stamp (ABI v9), not the pull instant — see
+                        // async_loop: a pull stamp folds hand-off queue wait into "network".
+                        let received_ns = if frame.received_ns > 0 {
+                            frame.received_ns as i128
+                        } else {
+                            now_realtime_ns()
+                        };
                         in_flight.push_back((frame.pts_ns / 1000, received_ns));
                         if in_flight.len() > IN_FLIGHT_CAP {
                             in_flight.pop_front(); // stale — codec never echoed it back