Disable PA on/off ramps; restore mainline to pre-ramp state

Three iterations of the Daikoku PA ramps never read as a real
interchange. Measured why, rather than tuning further:

  * the entry and exit decks INTERSECTED -- 2547 sample pairs within
    30 studs horizontally at <12 studs dY, worst case 0.5 studs apart
    at dY=0.0. On screen that is the bowtie tangle of white rails.
  * both real Daikoku ramps turn the SAME way (clockwise; the guide
    video says "right, right"). This build mirrored them into each
    other.
  * the real arc wraps OUTSIDE the lot and forms its north/east
    boundary. This build cut across the apron interior.

Gated behind BUILD_PA_RAMPS=false rather than deleted -- the radius
was already correct (470 studs vs an OSM-measured mean of 469) and
the merge lands tangent at 0.1-0.2 deg divergence. Both worth keeping.

Also removed two leftovers that would have outlived the ramps:

  * rampOpen punched holes in the mainline's outer parapet, railing
    and kill wall for ramps that no longer exist -- a barrier gap with
    a drop behind it. Sealed via RAMP_EDGE_OPENINGS=false. Verified:
    Barrier/EdgeRail/KillWall = 1646 each = 823 samples x 2 edges,
    0 road samples without a guard within 90 studs.
  * gore zebra hatching painted 1024 bars + 64 boundary lines marking
    a junction that is not there. Sealed via RAMP_GORE_MARKINGS=false.

Verified after a cache-busting fresh rebuild (Studio's require() cache
otherwise serves the previous map and reports a false pass):
  parts 22628 -> 15988
  all ramp part classes = 0
  Road = 823 (unchanged), spawn pad + PASpawn intact
  clip probe TRUSTWORTHY (control +11/-0), CLIPPING=0

Research and rebuild spec kept for when this is revisited:
reference/ramps/BUILD_SPEC.md, INDEX.md (10 CC-licensed Commons
photos), docs/daikoku-reference-spec.md (OSM circle fits).

tools/capture_defects.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+"""Eyes-on shots at the two REPORTED defects (not generic beauty angles).
+
+Targets:
+  A  entry ramp start        (-4122, 47, -7860)  -- the 390-stud access gap
+  B  exit ramp start         (-4258, 47, -7836)
+  C  mainline junction       (-3700, 102, -7184) -- the dY -6.0 step
+  D  ramp vs nearest building(-4419, 223, -6751)
+"""
+import shutil
+import sys
+import time
+
+sys.path.insert(0, "/tmp")
+import rbx  # noqa: E402
+
+OUT = "/home/jesse/roblox/tokyo-wangan-racing/tools/shots"
+
+SHOTS = [
+    # name, camera pos, look-at
+    ("D1_entry_ramp_start", (-4122 + 210, 47 + 120, -7860 + 210), (-4122, 47, -7860)),
+    ("D2_entry_start_low", (-4122 + 70, 47 + 25, -7860 + 70), (-4122, 55, -7860)),
+    ("D3_exit_ramp_start", (-4258 - 200, 47 + 110, -7836 + 200), (-4258, 47, -7836)),
+    ("D4_junction_step", (-3700 + 190, 102 + 90, -7184 + 190), (-3700, 102, -7184)),
+    ("D5_ramp_vs_building", (-4419 + 520, 223 + 180, -6751 + 520), (-4300, 120, -7100)),
+    ("D6_corridor_along", (-4122, 47 + 260, -7860 + 480), (-4300, 110, -7200)),
+]
+
+CAM = """
+local cam = workspace.CurrentCamera
+cam.CameraType = Enum.CameraType.Scriptable
+cam.FieldOfView = {fov}
+cam.CFrame = CFrame.lookAt(Vector3.new({px},{py},{pz}), Vector3.new({tx},{ty},{tz}))
+return "ok"
+"""
+
+
+def main():
+    made = []
+    for name, (px, py, pz), (tx, ty, tz) in SHOTS:
+        fov = 70 if "low" in name or "along" in name else 55
+        r = rbx.call(
+            "execute_luau",
+            {
+                "datamodel_type": "Edit",
+                "code": CAM.format(
+                    fov=fov, px=px, py=py, pz=pz, tx=tx, ty=ty, tz=tz
+                ),
+            },
+            wait=12,
+            timeout=300,
+        )
+        if isinstance(r, dict) and r.get("isError"):
+            print(f"{name}: CAM FAIL {str(r)[:120]}")
+            continue
+        time.sleep(1.5)
+        cap = rbx.call(
+            "screen_capture", {"capture_id": "ScreenCapture_1"}, wait=22, timeout=300
+        )
+        imgs = cap.get("images") if isinstance(cap, dict) else None
+        if not imgs:
+            print(f"{name}: CAPTURE FAIL {str(cap)[:140]}")
+            continue
+        dest = f"{OUT}/{name}.jpg"
+        shutil.copy(imgs[0], dest)
+        made.append(dest)
+        print(f"{name}: OK -> {dest}")
+    print(f"\nMADE {len(made)}")
+
+
+if __name__ == "__main__":
+    main()