wip(assembler): round L33 -- SurfaceWorld can be an upper strate; FloorProfileBlend measures seams

Route planning for an upper SurfaceWorld failed on long candidate chords over steep relief; chords
are now capped to the arrival/departure radii on an 8 m centre grid with an origin-proximity cost
(21.5 m walk, about 4 deg). The departure passage starts at the SW ground and tunnels down through rock.
FI -> SW -> TN fixture: all 4 styles pass every passage audit on both compilers. FloorProfileBlend
now checks endpoint height/tangent seams (step and tangent-step negative controls detected). Owner
world hashes unchanged; 30/30 determinism; cost within noise.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Standalone/Research/WorldAssemblerM3/Linux33/BuildUpperSurfaceFixtureL33.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+"""Build owner-like FloatingIslands -> SurfaceWorld -> TunnelNetwork fixtures."""
+import copy
+import json
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[4]
+SOURCE = ROOT / "Standalone/data/owner_world.json"
+OUT = ROOT / "Saved/Linux/l33/fixtures"
+
+
+def make_fixture(style: int) -> Path:
+    world = json.loads(SOURCE.read_text(encoding="utf-8"))
+    source_tunnel, source_surface = world["strates"]
+
+    floating = copy.deepcopy(source_tunnel)
+    floating.update(index=0, top_chunk_z=0, bottom_chunk_z=-15, height_chunks=16)
+    floating["asset"]["StrateName"] = "Linux33 Upper FloatingIslands"
+    floating["asset"]["StrateHeightInChunks"] = 16
+    floating["asset"]["GeneratorType"] = 6
+
+    surface = copy.deepcopy(source_surface)
+    surface.update(index=1, top_chunk_z=-16, bottom_chunk_z=-79, height_chunks=64)
+    surface["asset"]["StrateName"] = "Linux33 Middle SurfaceWorld"
+    surface["asset"]["StrateHeightInChunks"] = 64
+    surface["asset"]["PassageConfig"]["Style"] = style
+    surface["passage_config"]["Style"] = style
+
+    tunnel = copy.deepcopy(source_tunnel)
+    tunnel.update(index=2, top_chunk_z=-80, bottom_chunk_z=-143, height_chunks=64)
+    tunnel["asset"]["StrateName"] = "Linux33 Lower TunnelNetwork"
+    tunnel["asset"]["StrateHeightInChunks"] = 64
+
+    world["strates"] = [floating, surface, tunnel]
+    world["total_strates"] = 3
+    world["settings_asset"]["TotalStrates"] = 3
+    world["settings_asset"]["StratePool"] = [
+        "/Standalone/Linux33/UpperFloatingIslands",
+        "/Standalone/Linux33/MiddleSurfaceWorld",
+        "/Standalone/Linux33/LowerTunnelNetwork",
+    ]
+    world["passages"] = []  # The L23 legacy coordinates are not part of this resolved stack.
+    world["source"] = "VoxelForge Linux33 owner-like SurfaceWorld-upper fixture"
+
+    OUT.mkdir(parents=True, exist_ok=True)
+    path = OUT / f"sw-upper-tunnel-network-style{style}.json"
+    path.write_text(json.dumps(world, separators=(",", ":")), encoding="utf-8")
+    return path
+
+
+if __name__ == "__main__":
+    for style in range(4):
+        path = make_fixture(style)
+        print(f"style={style} fixture={path}")