fix(capture/vdisplay): descriptor-following defers while a topology reassert is in flight

The exclusive-topology reassert's forced re-commit transiently bounces the
virtual display's mode; the descriptor poller can sample that EVICTION state
and recreate the ring at a mode the recovery chain is about to undo (field
log 2026-07-27 10:30:44Z: hdr=true → false → recreate → recovery restores
true → second recreate). New pf-win-display::topology_churn latch (deadline
semantics — self-expiring, so a lost release can never wedge descriptor-
following off): the watchdog holds it for interval+3s each fighting round and
releases on "stable again"; poll_display_hdr consumes samples but acts on
nothing while held — which also keeps the negotiated-depth pin-back from
issuing a CCD write mid-eviction, where it would fight the reassert itself.
The deliberate recreate_ring_in_place recovery path is unaffected.

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

crates/pf-capture/src/windows/idd_push.rs

@@ -732,6 +732,18 @@ impl IddPushCapturer {
             return; // no new sample since last consume
         }
         self.desc_seq = seq;
+        // A topology reassert is in flight (the exclusive watchdog announced it): every sample in
+        // this window is potentially the TRANSIENT eviction state, and acting on one recreates
+        // the ring at a mode the reassert's recovery chain (`recreate_ring_in_place`, keyed off
+        // the reassert generation) is about to undo — the field hdr=true→false→true double
+        // recreate. Consume the sample, disarm the debounce, act on nothing; a REAL change that
+        // races the window survives it (the descriptor still differs once the hold clears, and
+        // the poller re-samples in ~250 ms). This also keeps the negotiated-depth pin-back below
+        // from issuing a CCD write mid-eviction, where it would fight the reassert itself.
+        if pf_win_display::topology_churn::held() {
+            self.pending_desc = None;
+            return;
+        }
         // Two cases re-assert the NEGOTIATED depth instead of following a mid-session "Use HDR"
         // flip — flip the display back and treat the descriptor as the negotiated state (so the ring
         // is never recreated at the wrong format):