passages: floor profile by nearest centreline + metric distance outside voids (L114, v222) - WIP

Floor ribs are present in L109/L112/L113 rock tunnels too: the floor height comes from the
nearest segment, so it jumps (up to 5.9-7.3 cm) where the nearest segment switches. v222 reduces
them; faint ribs remain. Quiet-machine timing (load 0.64): near-ready 9-17% slower than L109
(FI W12 0.95 -> 1.10 s); candidate totals ~5x L109. Fast tier FAIL: 2 SW wall-shell probes of
31,381 read host air. Walk/grade audits pass; Clang/GCC deterministic; UE builds.

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

Standalone/Research/WorldAssemblerM3/Linux114/RunL114DensityProbe.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""Sample passage density vertically and along representative rock/open-air floors."""
+from __future__ import annotations
+
+import os
+import subprocess
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[4]
+OUT = ROOT / "Saved/Linux/l114"
+BINARY = ROOT / "Saved/Linux/l114/bin/VoxelForgeCoreHeadless-l114-clang"
+DATA = ROOT / "Standalone/data/owner_world.json"
+
+
+def main() -> int:
+    OUT.mkdir(parents=True, exist_ok=True)
+    log = OUT / "audit-owner-clang.log"
+    layout = OUT / "audit-layout-candidate.json"
+    command = [
+        "taskset", "-c", "0-11", "prlimit", "--as=6442450944", "--",
+        "timeout", "1740s", str(BINARY), str(DATA), "--world-assembler-prototype",
+        "--stream-benchmark", "--stream-pipeline", "--workers=12", "--clip-radius=3",
+        "--max-clip-level=8", "--max-level=8", "--camera=8,16,-372.2626953125,0,0",
+        "--audit-resolved-layout-passages", f"--resolved-layout-output={layout}",
+    ]
+    with log.open("w", encoding="utf-8") as stream:
+        result = subprocess.run(command, cwd=ROOT,
+                                env={**os.environ,
+                                     "VOXELFORGE_L114_DENSITY_PROFILE": "1"},
+                                stdout=stream, stderr=subprocess.STDOUT,
+                                check=False, timeout=1740)
+    print(f"[L114DensityProbe] exit={result.returncode} log={log.relative_to(ROOT)}",
+          flush=True)
+    return result.returncode
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())