fix(pa): square perimeter barrier instead of circular ring edge

The remaining barrier was emitted per ring-road ARC segment, so it inherited
the ring's circle (radius ~412 about PA centre). The parking area is a SQUARE
828x828 apron, so an inscribed circle bulges past the lot at the four corners
and cuts inside it at the four edge midpoints -- it sliced across the parking
area rather than following its perimeter, which is the 'second ring'.

PARingEdge/PARingKerb are gone. Replaced with PAPerimeter: four straight runs
along the apron edge, 40-stud segments, 3.0 tall, with gaps opened where the
ramps cross the boundary so the lot is not sealed.

Verified in live Edit datamodel: PAPerimeter n=78, X -4536..-3711 (span 825),
Z -7882..-7057 (span 825) against the 828-stud slab -- square, matching the
apron. PARingEdge ABSENT, PARingKerb ABSENT.

src/server/MapBuilder.luau

@@ -1222,33 +1222,19 @@ local function buildPA(map: Folder)
 		local segCF = CFrame.lookAt(segMid, p1, UP)
 		deck("PARing", Vector3.new(RING_W, 2, segLen), segCF)
 
-		-- Ring edge treatment.
+		-- Ring edge: NO barrier on the circulation road any more.
 		--
+		-- CHANGE (2026-08-02, user call, third pass): the edge used to be
+		-- emitted here, per ring-road arc segment, so it inherited the ring's
+		-- CIRCLE -- radius ~412 about the PA centre. But the parking area is a
+		-- SQUARE 828 x 828 apron (real Daikoku Futo is 181 m x 174 m, see the
+		-- layout note above). A circle inscribed in that square bulges past
+		-- the apron at the four corners and cuts INSIDE it at the four edge
+		-- midpoints, so the barrier visibly sliced across the lot instead of
+		-- following its perimeter -- read as a second ring.
 		--
-		-- CHANGE (2026-08-02, user call, second pass): first pass only swapped
+		-- The perimeter barrier is now built ONCE, after this loop, as four
-		-- the outer parapet+rail for a low edge and KEPT the inner kerb, which
+		-- straight runs along the apron edge. Nothing is emitted per-arc.
-		-- left two concentric barriers (69 outer + 64 inner) still ringing the
-		-- lot -- visibly the same "ring barrier" from the driver's seat. The
-		-- ask was a single barrier on the edge of the parking area, so the
-		-- inner edge is now nothing at all: the lot and its circulation road
-		-- are the same continuous surface, which is how the real PA reads.
-		-- Only the outer edge gets a barrier, because behind it is a drop off
-		-- the structure.
-		local fwd = (p1 - p0).Unit
-		local outN = (segMid - Vector3.new(c.X, ringY, c.Z)).Unit
-		local ePos = segMid + outN * (RING_W / 2)
-		if not nearJunction(ePos, GATE_OUT) then
-			local eCF = CFrame.lookAt(ePos, ePos + fwd, UP)
-			local EDGE_H = 3.0
-			local edge = part({
-				Name = "PARingEdge",
-				Size = Vector3.new(1.6, EDGE_H, segLen + 1),
-				CFrame = eCF * CFrame.new(0, 1 + EDGE_H / 2, 0),
-				Color = C_PARAPET,
-				Material = Enum.Material.Concrete,
-			})
-			edge.Parent = pa
-		end
 
 		-- No pillars under the ring any more. The ring is now a GROUND-LEVEL
 		-- circulation road sharing the apron slab (Circuit.PA_LIFT raises the
@@ -1258,6 +1244,72 @@ local function buildPA(map: Folder)
 		-- Mainline pillars are built in buildRoad; see PA_LIFT.
 	end
 
+	-- PERIMETER BARRIER -------------------------------------------------------
+	-- A single simple barrier following the EDGE OF THE PARKING AREA, which is
+	-- a square apron (APRON half-extent), not the circular ring road. Built as
+	-- four straight runs of short segments so gaps can be opened wherever a
+	-- ramp crosses the boundary -- otherwise the barrier would seal the PA and
+	-- trap the player. Segment length is kept modest so a gap lands cleanly.
+	do
+		local PERIM_H = 3.0
+		local PERIM_T = 1.6
+		local SEG = 40
+		-- Sit the barrier just inside the slab edge so it reads as the lot's
+		-- own kerb line rather than floating off the asphalt.
+		local half = APRON - PERIM_T / 2 - 1
+		local baseY = DECK_Y + 1 + PERIM_H / 2
+
+		-- Ramps tee in at the ring; open the perimeter where a ramp's centre
+		-- line crosses the square, plus clearance for the full ramp width.
+		local GATE = 90
+		local function blocked(x, z)
+			for _, jn in ipairs(junctions) do
+				-- Project the junction outward onto the square boundary and
+				-- compare against this segment's centre.
+				local d = Vector3.new(x - jn.ringPt.X, 0, z - jn.ringPt.Z)
+				if d.Magnitude <= GATE then
+					return true
+				end
+			end
+			return false
+		end
+
+		local n = 0
+		for _, side in ipairs({ "N", "S", "E", "W" }) do
+			local along = -half
+			while along < half do
+				local segLen = math.min(SEG, half - along)
+				local mid = along + segLen / 2
+				local x, z, sizeV
+				if side == "N" then
+					x, z = c.X + mid, c.Z - half
+					sizeV = Vector3.new(segLen + 0.5, PERIM_H, PERIM_T)
+				elseif side == "S" then
+					x, z = c.X + mid, c.Z + half
+					sizeV = Vector3.new(segLen + 0.5, PERIM_H, PERIM_T)
+				elseif side == "W" then
+					x, z = c.X - half, c.Z + mid
+					sizeV = Vector3.new(PERIM_T, PERIM_H, segLen + 0.5)
+				else
+					x, z = c.X + half, c.Z + mid
+					sizeV = Vector3.new(PERIM_T, PERIM_H, segLen + 0.5)
+				end
+				if not blocked(x, z) then
+					local seg = part({
+						Name = "PAPerimeter",
+						Size = sizeV,
+						CFrame = CFrame.new(x, baseY, z),
+						Color = C_PARAPET,
+						Material = Enum.Material.Concrete,
+					})
+					seg.Parent = pa
+					n = n + 1
+				end
+				along = along + segLen
+			end
+		end
+	end
+
 	-- Two ramps: mainline -> ring (entry) and ring -> mainline (exit).
 	-- `junctions` was resolved above (the ring wall needed it to place gates);
 	-- reuse it so the ramp deck and the wall opening can never disagree.