streaming: deeper ready queue + startup apply cap; tile-local mouth-support culling (L72)

- Unreal: ready queue depth 8 -> 16 (cap 4 worker-sets / 64), startup mesh-apply cap
  12 -> 24 within the unchanged 14 ms budget. Owner SW arrival, same 2,850 keys:
  initial set ready 4.78 -> 3.74 s, queue p95 123 -> 35 ms, request-to-apply p95
  139 -> 45 ms; walkable gate 1.07 -> 1.11 s; per-frame apply p95 0.73 ms.
- Core composer: mouth-support segments filtered by tile bounds, mouth relief result reused
  (route checks -80/-87% in passage tiles). Hashes identical W1/W8/W12, Clang and GCC.
- Opt-in per-tile composer counters. Verify control meshes stored as .xz (78.5 -> 18.4 MB).
- Fast tier 269 PASS.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016dhxM43dnWvUu2B5Ph1iG1

Standalone/Source/StreamBenchmarkPipeline.h

@@ -1872,7 +1872,8 @@ namespace StandaloneStreamBenchmark
         bool bExactMidpointDensityMemo=false,
         bool bActiveLaneBatching=false,int32 ProofBlockCells=8,
         bool bParallelSignEdgeRepair=false,bool bAuditNativeLattice=false,
-        bool bLatticeOrphanControl=false,bool bCaptureSkipWalkability=false)
+        bool bLatticeOrphanControl=false,bool bCaptureSkipWalkability=false,
+        bool bProfilePassageComposer=false)
     {
         using Clock=std::chrono::steady_clock;
         FStandaloneOwnerWorld& World=*OwnerWorld;
@@ -2037,6 +2038,7 @@ namespace StandaloneStreamBenchmark
             FarHorizonLOD8InteriorStepVoxels,bUseSharedColumnCache);
         Streamer.SetUniformBlockProofAuditEnabled(bAuditUniformBlockProofs);
         Streamer.SetTileDrainInstrumentationEnabled(bInstrumentTileDrain);
+        Streamer.SetPassageComposerProfilingEnabled(bProfilePassageComposer);
         Streamer.SetExactMidpointDensityMemoEnabled(bExactMidpointDensityMemo);
         Streamer.SetActiveLaneBatchingEnabled(bActiveLaneBatching);
         Streamer.SetProofBlockCells(ProofBlockCells);