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_regression.luau

@@ -0,0 +1,151 @@
+-- READ-ONLY REGRESSION CHECK. Does NOT build. Inspects whatever is currently
+-- in Studio and compares against every property we had verified as good, so we
+-- can tell whether the last edits preserved the good version or damaged it.
+--
+-- Known-good baseline (measured earlier this session):
+--   ramp PAEastSlip total bend 30.7deg, worst 1.3, over5=0, level run 20
+--   ramp PAWestSlip total bend 34.4deg, worst 1.4, over5=0, level run 20
+--   AuxLane parts = 30   (user's hand-edited count, NOT the source's 52)
+--   unguarded deck edges = 0 across all 823 samples
+--   parts ~= 16788
+local out = {}
+local function say(s) table.insert(out, s) end
+
+local map = workspace:FindFirstChild("Map")
+if not map then return "Map MISSING -- nothing built" end
+
+local UP = Vector3.new(0, 1, 0)
+local function flat(v) return Vector3.new(v.X, 0, v.Z) end
+
+local parts = 0
+local deck, aux, bars, slipParts = {}, {}, {}, {}
+for _, d in ipairs(map:GetDescendants()) do
+	if d:IsA("BasePart") then
+		parts += 1
+		local k = d.Name:match("^Road_(%d+)$") or d.Name:match("^Deck_(%d+)$")
+		if k then deck[tonumber(k)] = d end
+		local a = d.Name:match("^AuxLane_(%d+)$")
+		if a then aux[tonumber(a)] = d end
+		if d.Name == "Barrier" or d.Name == "EdgeRail" then table.insert(bars, d) end
+		if d.Name:match("Slip") then table.insert(slipParts, d) end
+	end
+end
+say(("parts = %d          (baseline ~16788)"):format(parts))
+
+-- 1. RAMP SMOOTHNESS -- the thing the user cares most about right now
+local rampOK = true
+for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+	local segs = {}
+	for _, d in ipairs(map:GetDescendants()) do
+		if d:IsA("BasePart") then
+			local k = d.Name:match("^" .. s .. "_Deck_(%d+)$")
+			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  <<< RAMP GONE")
+		rampOK = false
+	else
+		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 dth = math.deg(math.acos(math.clamp(a:Dot(b), -1, 1)))
+			total += dth
+			if dth > worst then worst = dth; worstAt = segs[j].i end
+			if dth > 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
+		if over > 0 then rampOK = false end
+		say(("%s: segs=%d total=%.1fdeg worst=%.1f@%d over5=%d level=%d %s"):format(
+			s, #segs, total, worst, worstAt, over, level,
+			over == 0 and "OK" or "<<< KINKED"))
+	end
+end
+say(rampOK and ">> RAMPS STILL SMOOTH" or ">> RAMP REGRESSION")
+
+-- 2. USER'S DELETED LANE -- must stay deleted
+local auxN, inRange = 0, 0
+for i in pairs(aux) do
+	auxN += 1
+	if i >= 525 and i <= 550 then inRange += 1 end
+end
+say(("AuxLane = %d (baseline 30) | inside deleted run 525..550 = %d (want 0) %s"):format(
+	auxN, inRange, (auxN == 30 and inRange == 0) and "OK" or "<<< REGRESSION"))
+
+-- 3. BARRIER COVERAGE -- full loop
+local holes = {}
+local swept = 0
+for i, d in pairs(deck) do
+	swept += 1
+	local right = d.CFrame.LookVector:Cross(UP).Unit
+	for _, sgn in ipairs({ -1, 1 }) do
+		local edge = d.Position + right * sgn * (d.Size.X / 2 + 2)
+		local bd = math.huge
+		for _, b in ipairs(bars) do
+			if math.abs(b.Position.Y - edge.Y) < 14 then
+				local dd = (flat(b.Position) - flat(edge)).Magnitude
+				if dd < bd then bd = dd end
+			end
+		end
+		if bd >= 12 then
+			local okb = false
+			local a = aux[i]
+			if a then
+				local outer = a.Position + right * sgn * (a.Size.X / 2 + 2)
+				local bd2 = math.huge
+				for _, b in ipairs(bars) do
+					if math.abs(b.Position.Y - outer.Y) < 14 then
+						local dd = (flat(b.Position) - flat(outer)).Magnitude
+						if dd < bd2 then bd2 = dd end
+					end
+				end
+				if bd2 < 14 then okb = true end
+			end
+			if not okb then
+				local sd = math.huge
+				for _, p in ipairs(slipParts) do
+					local dd = (flat(p.Position) - flat(edge)).Magnitude
+					if dd < sd then sd = dd end
+				end
+				if sd > 30 then table.insert(holes, i .. (sgn < 0 and "L" or "R")) end
+			end
+		end
+	end
+end
+say(("barrier sweep: %d samples, unguarded=%d %s"):format(swept, #holes,
+	#holes == 0 and "OK" or ("<<< " .. table.concat(holes, ","))))
+
+-- 4. FENCE JOG at the suppression boundary
+local prevLat, jogs = nil, {}
+for i = 505, 570 do
+	local d = deck[i]
+	if d then
+		local right = d.CFrame.LookVector:Cross(UP).Unit
+		local best, bestLat = math.huge, nil
+		for _, b in ipairs(bars) do
+			if b.Name == "Barrier" and math.abs(b.Position.Y - d.Position.Y) < 14 then
+				local rel = b.Position - d.Position
+				local along = math.abs(rel:Dot(d.CFrame.LookVector))
+				local lat = rel:Dot(right)
+				if along < 22 and lat < 0 and along < best then best = along; bestLat = lat end
+			end
+		end
+		if bestLat then
+			if prevLat then
+				local step = math.abs(math.abs(bestLat) - math.abs(prevLat))
+				if step > 10 then table.insert(jogs, ("%d(%.1f)"):format(i, step)) end
+			end
+			prevLat = bestLat
+		else
+			prevLat = nil
+		end
+	end
+end
+say(("fence jogs >10 studs: %d %s"):format(#jogs,
+	#jogs == 0 and "OK" or ("<<< " .. table.concat(jogs, " "))))
+
+return table.concat(out, "\n")