wip(gate): request the support tile at once; no gate timeout -- stress criteria NOT trusted yet

- RequestCollisionGateSupportTile submits the level-0 support tile immediately, even before the
  first desired set; the desired rebuild adopts the same pending key (1 early request, 1 adoption,
  1 ready callback in all 10 runs). First check -> submit went from ~2.2 s to ~1 us.
- The 2 s gate release timeout is removed: at the owner's startup the game thread applies nothing
  for ~2.2 s, so the timeout always fired and dropped the pawn. The gate holds downward Z only;
  horizontal movement stays free.
- Controls (previous round): legacy selector+reconcile failed the stress repro 0/5, aligned 1/5,
  so 85a803b did not regress the gate.

NOT VALIDATED: the stress repro's pass criteria were rewritten (support submitted/ready, a hold,
progress during a hold). 10/10 "pass" under them, but every one of those runs, and the gate-
disabled run, ends stuck at (455.7, 0, -58.1), ~1.55 m below the Z~97-100 at which the old
passing runs travelled 113 m. Whether that spot is a real pit or the pawn below the surface is
unresolved; until it is, a pass under these criteria proves nothing about falling through.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Source/VoxelForge/Public/VoxelWorld.h

@@ -1118,6 +1118,7 @@ public:
     double HeadlessCollisionGateStressTestGateStartSeconds = 0.0;
     double HeadlessCollisionGateStressTestFullStopStartSeconds = 0.0;
     double HeadlessCollisionGateStressTestDistanceCm = 0.0;
+    double HeadlessCollisionGateStressTestGateDistanceCm = 0.0;
     double HeadlessCollisionGateStressTestTotalGateDurationSeconds = 0.0;
     double HeadlessCollisionGateStressTestMaxGateDurationSeconds = 0.0;
     double HeadlessCollisionGateStressTestFullStopDurationSeconds = 0.0;
@@ -1226,6 +1227,14 @@ public:
     bool bPawnGateUnsupportedReported = false;
     FVoxelTileKey PawnGateRequestedSupportTile;
     bool bPawnGateSupportRequestReported = false;
+    // Keep the first unresolved support request's timing for the startup gate repro. This is
+    // intentionally retained after release so the stress-test result can report the bootstrap path.
+    FVoxelTileKey StartupCollisionGateSupportTile;
+    bool bStartupCollisionGateTimingCaptured = false;
+    bool bStartupCollisionGateAdoptionReported = false;
+    double StartupCollisionGateFirstCheckSeconds = 0.0;
+    double StartupCollisionGateSubmittedSeconds = 0.0;
+    double StartupCollisionGateReadySeconds = 0.0;
 
     // Desired-set membership STAMPÉE : clé → numéro du dernier crossing où la tuile était désirée.
     // BuildDesiredTiles upserte le stamp courant puis balaie la map UNE fois : les entrées à stamp