fix(streaming): collision-ready gate -- the pawn waits for a COOKED floor, not a submitted one

WORK-NEXT item 1, plus all three of item 6. Item 2 (the fused evaluator) untouched as
instructed.

⭐ RMC DOES EXPOSE WHAT WE NEEDED, so the gate rests on a real signal:
  OnCollisionBodyUpdated                              (delegate -- diagnostic)
  SetCollisionConfig() -> TFuture<ERealtimeMeshCollisionUpdateResult>  (AUTHORITATIVE)
RealtimeMeshComponent was READ ONLY, per the owner's grant. Nothing there was modified.

THE INVARIANT
Until now nothing guaranteed a tile the player occupies has collision. apply_s ended at
mesh SUBMISSION; RMC cooks asynchronously and we recorded no completion, so no
measurement this project has ever taken said when physics could actually collide.

  - per-tile CollisionReadyTiles state, with stale-callback protection
  - HandleTileCollisionCookComplete driven by RMC's cook future
  - pawn gated at BeginPlay and pre-physics on the FEET-SUPPORT tile -- deliberately not
    the actor-centre tile, because the floor that catches a falling pawn is what must be
    cooked -- plus the predicted movement path and solid/air traversal
  - movement-component state saved/restored, so a temporary stream wait cannot
    permanently change a character's movement mode
  - new trace fields: mesh_submit_to_cook_s, collision_request_to_cook_s,
    body_event_to_future_s -- three boundaries where we had one blurred number

ITEM 6, all three:
  - LoadedTiles is now recorded only after SUCCESSFUL mesh submission, and a failed
    mesh init retries. Previously a failed init left a tile marked loaded forever -- a
    permanent hole.
  - origin spawning fixed (the zero-position guard made a pawn at exactly
    FVector::ZeroVector indistinguishable from "no pawn" -- and the owner spawns at 0,0)
  - exact core-lattice validation for uniform whole-tile verdicts, which previously had
    no safety net while block verdicts did

⚠️ I FIXED TWO COMPILE ERRORS MYSELF rather than spend another Codex round on them:
`GetMovementMode()` / `GetCustomMovementMode()` do not exist on
UCharacterMovementComponent -- MovementMode and CustomMovementMode are public fields.
Two lines. Codex did not build this round, so it could not have caught them.

VERIFIED BY ME: build 0 errors after the patch; export 1.022 / 1.055 s (aa62971 was
1.034 / 1.089); geometry SHA-256 b3e5f4c3..9b377 UNCHANGED -- generation is untouched,
as it should be for a streaming-lifecycle change.

⚠️ UNVERIFIED AND IMPORTANT: the submission-to-cook gap is still unmeasured -- Codex had
no live process to measure it in. The instrumentation exists and will report it on the
next play session. And the GATE ITSELF IS UNTESTED IN MOTION: if a support tile never
becomes collision-ready, the pawn stays frozen rather than falling. That trade is
deliberate, but the owner should watch for it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aheo2crrZmHuYtPpdY2Cb

Source/VoxelForge/Private/VoxelStartupTrace.cpp

@@ -113,7 +113,7 @@ namespace
             if (Sample.bCacheHit) ++CacheHits;
             if (Sample.bRegionHit) ++RegionHits;
             Triangles += Sample.Triangles;
-            Request.Add(Sample.RequestToReadySeconds);
+            Request.Add(Sample.RequestToApplySeconds);
             Queue.Add(Sample.QueueWaitSeconds);
             Generation.Add(Sample.GenerationSeconds);
             Classify.Add(Sample.ClassifySeconds);
@@ -123,7 +123,7 @@ namespace
 
         return FString::Printf(
             TEXT("{\"count\":%d,\"empty\":%d,\"all_air\":%d,\"all_solid\":%d,\"mixed\":%d,\"cache_hits\":%d,\"region_hits\":%d,\"triangles\":%lld,"
-                 "\"request_ready_s\":{\"p50\":%s,\"p95\":%s,\"max\":%s},"
+                 "\"request_apply_s\":{\"p50\":%s,\"p95\":%s,\"max\":%s},"
                  "\"queue_s\":{\"p50\":%s,\"p95\":%s,\"max\":%s},"
                  "\"generation_s\":{\"p50\":%s,\"p95\":%s,\"max\":%s},"
                  "\"classify_s\":{\"p50\":%s,\"p95\":%s,\"max\":%s},"
@@ -265,11 +265,11 @@ void RecordTile(const FTileSample& Sample)
     ++GState->TileRecordsWritten;
     WriteEventLocked(*GState, TEXT("tile"), FString::Printf(
         TEXT("\"level\":%d,\"verdict\":%d,\"empty\":%d,\"cache_hit\":%d,\"region_hit\":%d,\"triangles\":%d,"
-             "\"request_to_ready_s\":%s,\"queue_wait_s\":%s,\"worker_queue_s\":%s,\"result_queue_s\":%s,"
+             "\"request_to_apply_s\":%s,\"queue_wait_s\":%s,\"worker_queue_s\":%s,\"result_queue_s\":%s,"
              "\"generation_s\":%s,\"classify_s\":%s,\"mesh_s\":%s,\"stream_s\":%s,\"apply_s\":%s"),
         Sample.Level, Sample.Verdict, Sample.bEmpty ? 1 : 0,
         Sample.bCacheHit ? 1 : 0, Sample.bRegionHit ? 1 : 0, Sample.Triangles,
-        *Number(Sample.RequestToReadySeconds), *Number(Sample.QueueWaitSeconds),
+        *Number(Sample.RequestToApplySeconds), *Number(Sample.QueueWaitSeconds),
         *Number(Sample.WorkerQueueSeconds), *Number(Sample.ResultQueueSeconds),
         *Number(Sample.GenerationSeconds), *Number(Sample.ClassifySeconds),
         *Number(Sample.MeshSeconds), *Number(Sample.StreamSeconds), *Number(Sample.ApplySeconds)));