passages: XY-smooth spline with planned height profile + open-air half-pipe (L112, v219)

Dense centripetal spline in XY, height piecewise-linear on the planner's certified profile,
radius/floor depth blended; open air = floor slab + 1 m side walls, no roof; audits sample the
generated centreline. All walk audits pass (grades <= 15 deg, headroom, shell, mouths, ripple);
Clang/GCC W1/W8/W12 deterministic; fast tier PASS; Linux UE builds. Chevron rings gone.
Open issues: jagged spikes along the half-pipe wall tops, visible step lines on the trough
floor; near-ready +7..+10% vs L109 (candidate list p95 4 -> 22). Not merged.

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

Standalone/Tools/verify/verify.py

@@ -122,11 +122,11 @@ RECIPE_RE = re.compile(
 
 def owner_hash_baseline(recipe: str, style: int) -> tuple[Path, str]:
     if recipe == "surface-world" and style == 1:
-        return (BASELINES / "owner-hash/canonical/owner-hash-surface-world-style1-v218.baseline",
-                "L111-v218-smooth-spline-half-pipe")
+        return (BASELINES / "owner-hash/canonical/owner-hash-surface-world-style1-v219.baseline",
+                "L112-v219-horizontal-spline-planned-grade-half-pipe")
     if recipe == "floating-islands" and style == 2:
-        return (BASELINES / "owner-hash/canonical/owner-hash-floating-islands-style2-v218.baseline",
-                "L111-v218-smooth-spline-half-pipe")
+        return (BASELINES / "owner-hash/canonical/owner-hash-floating-islands-style2-v219.baseline",
+                "L112-v219-horizontal-spline-planned-grade-half-pipe")
     raise VerificationFailure(f"no pinned owner hash baseline for {recipe} style {style}")