Aux-lane suppression + PA geometry fixes; probe/verify tooling

MapBuilder.luau
  - Suppress the aux lane across samples 525-550 (AUX_SUPPRESS_FROM/TO),
    honoring the user's hand deletion in Studio so a rebuild no longer
    regenerates it.
  - Smoothstep the width ramp over AUX_BLEND=5 samples on each side. A hard
    cut produced a 26-stud lateral fence jog; the blend removes it.
  - DO NOT remove this suppression. Re-enabling it resurrects geometry the
    user deleted by hand.

rokit.toml
  - rojo 7.5.1 -> 7.7.0 to match the auto-updating Studio plugin.
    Server older than plugin fails the handshake with
    "attempt to index number with 'protocolVersion'".

tools/
  - 34 read-only probe/verify/capture scripts used to measure the datamodel
    instead of reasoning from source.

Verified-good baseline at this commit:
  total parts       16788
  PAWestSlip        60 segs, 34.4 deg total bend, worst 1.4, 0 kinks >5
  PAEastSlip        60 segs, 30.7 deg total bend, worst 1.3, 0 kinks >5
  AuxLane parts     30 (samples 525-550 deliberately absent)
  barrier coverage  823 samples, 0 unguarded
  fence jogs >10st  0

tools/probe_smoothed.luau

@@ -0,0 +1,69 @@
+-- Rebuild with the smoothing pass, then re-measure the SAME metrics as before
+-- so the before/after is directly comparable. Target: east total heading change
+-- down from 216deg toward the west's ~56deg, and ZERO segments turning >5deg
+-- (the 58.2/50.1deg hinges must be gone). Also verify the parallel run and
+-- the endpoints did not move -- smoothing must not detach the mouth.
+local SS = game:GetService("ServerScriptService")
+local out = {}
+local function say(s) table.insert(out, s) end
+
+local mod = SS:FindFirstChild("MapBuilder", true)
+if not mod then return "MapBuilder module NOT FOUND" end
+
+local ok, MB = pcall(require, mod)
+if not ok then return "require failed: " .. tostring(MB) end
+
+local t0 = os.clock()
+local ok2, err = pcall(function() MB.build() end)
+if not ok2 then return "build ERROR: " .. tostring(err) end
+say(("build OK (%.2fs)"):format(os.clock() - t0))
+
+local map = workspace:FindFirstChild("Map")
+if not map then return "Map missing after build" end
+
+local parts = 0
+for _, d in ipairs(map:GetDescendants()) do
+	if d:IsA("BasePart") then parts += 1 end
+end
+say(("parts=%d"):format(parts))
+
+for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+	local segs = {}
+	for _, d in ipairs(map:GetDescendants()) do
+		if d:IsA("BasePart") then
+			local k = d.Name:match("^" .. s .. "_Deck_(%d+)$")
+			if k then table.insert(segs, { i = tonumber(k), p = d.Position, cf = d.CFrame }) end
+		end
+	end
+	table.sort(segs, function(a, b) return a.i < b.i end)
+	if #segs == 0 then say(s .. ": ABSENT") continue end
+
+	local total, worst, worstAt, over = 0, 0, -1, 0
+	for j = 2, #segs do
+		local a, b = segs[j - 1].cf.LookVector, segs[j].cf.LookVector
+		local d = math.deg(math.acos(math.clamp(a:Dot(b), -1, 1)))
+		total += d
+		if d > worst then worst = d; worstAt = segs[j].i end
+		if d > 5 then over += 1 end
+	end
+
+	local topY, level = segs[1].p.Y, 0
+	for _, sg in ipairs(segs) do
+		if math.abs(sg.p.Y - topY) < 0.5 then level += 1 else break end
+	end
+
+	local lmin, lmax = math.huge, -math.huge
+	for j = 2, #segs do
+		local L = (segs[j].p - segs[j - 1].p).Magnitude
+		lmin = math.min(lmin, L); lmax = math.max(lmax, L)
+	end
+
+	say(("%s: segs=%d total=%.1fdeg mean=%.2f worst=%.1f@%d over5=%d"):format(
+		s, #segs, total, total / (#segs - 1), worst, worstAt, over))
+	say(("   level-run=%d startY=%.1f endY=%.1f spacing=%.1f..%.1f"):format(
+		level, segs[1].p.Y, segs[#segs].p.Y, lmin, lmax))
+	say(("   start=(%.0f,%.0f,%.0f) end=(%.0f,%.0f,%.0f)"):format(
+		segs[1].p.X, segs[1].p.Y, segs[1].p.Z, segs[#segs].p.X, segs[#segs].p.Y, segs[#segs].p.Z))
+end
+
+return table.concat(out, "\n")