wip(assembler): round S13 -- tile cost counted per LOD (diagnostics only, no output change)

Exclusive per-stage tile timers and probes. Findings: LOD0 is MC-exclusive
(10.4 of 14 ms p95, 243 ns/sample); LOD4's 3x cost is column-cache misses
(8,224 vs ~1,600-1,900 at LOD3/5), cap refine secondary; per-tile feature lists
cost ~0.001 ms; cross-worker column repeats common (277k at LOD0). Global octave
drop and stride-2 interpolation probes fail the 2 cm gate. Worker cap 1 kept
(cap 0 worse 40 m/s tick tail). Report: Standalone/Research/WorldAssemblerM3/Round17.

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

CODEMAP.md

@@ -1083,6 +1083,18 @@ submit/start/end times and the OS worker thread ID. No tile generation, mesh, de
 Core recipe output changes; recipe versions remain unchanged. See ARCHITECTURE §8.33 and
 [`Standalone/Research/WorldAssemblerM3/Round16/REPORT.md`](Standalone/Research/WorldAssemblerM3/Round16/REPORT.md).
 
+### 3.19 Exclusive tile cost and all-LOD column overlap — World Assembler S13 / M3 Round 17
+
+`VoxelForgeCore::TileGenerationStats` now exposes classification-exclusive time and the column
+evaluation performed during marching cubes, ground refinement, and cap refinement. The BuildHost
+shared-feature audit reports these p95 stages and per-density-sample costs for owner SurfaceWorld
+tiles at LOD0, 1, 3, 4, 5, and 8. Standalone `--profile-column-overlap` opts into XY miss-coordinate
+capture for all LODs and reports repeated evaluations across same-LOD tiles and workers; the older
+`--profile-far-column-overlap` spelling remains an alias. `--profile-column-overlap` changes no
+generation output. Measurement-only stride and octave probes are confined to the shared-feature
+audit and are not runtime controls. The result and limits are recorded in
+[`Standalone/Research/WorldAssemblerM3/Round17/REPORT.md`](Standalone/Research/WorldAssemblerM3/Round17/REPORT.md).
+
 ## 4. The density pipeline (most-edited hot path)
 
 ### 4.1 `GetDensityWithParams` (TunnelNetwork) — VoxelGenerator.cpp:3749