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_revert.luau

@@ -0,0 +1,74 @@
+-- "Changes were reverted" -- WHERE? Distinguish three separate states that can
+-- each independently be stale:
+--   (a) the MapBuilder SOURCE inside Studio (Rojo sync state)
+--   (b) the BUILT geometry sitting in workspace (may predate the source)
+--   (c) the place file itself
+local out = {}
+local function say(s) table.insert(out, s) end
+
+say("place: " .. tostring(game.Name))
+
+-- (a) SOURCE state in Studio
+local SS = game:GetService("ServerScriptService")
+local mb
+for _, d in ipairs(SS:GetDescendants()) do
+	if d:IsA("ModuleScript") and d.Name == "MapBuilder" then mb = d end
+end
+if not mb then
+	say("SOURCE: MapBuilder NOT FOUND in ServerScriptService")
+else
+	local ok, src = pcall(function() return mb.Source end)
+	if ok and type(src) == "string" then
+		say(("SOURCE: len=%d  PARALLEL_RUN=%s  PA_DEC_SPAN=%s  PA_SLIP=%s"):format(
+			#src,
+			tostring(src:find("PARALLEL_RUN") ~= nil),
+			tostring(src:find("PA_DEC_SPAN") ~= nil),
+			tostring(src:find("local PA_SLIP") ~= nil)))
+	else
+		say("SOURCE: unreadable " .. tostring(src))
+	end
+end
+
+-- (b) BUILT geometry actually in the workspace right now
+local map = workspace:FindFirstChild("Map")
+if not map then
+	say("BUILT: workspace.Map MISSING")
+	return table.concat(out, "\n")
+end
+
+local slipSegs, auxSegs = {}, 0
+for _, d in ipairs(map:GetDescendants()) do
+	if d:IsA("BasePart") then
+		for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+			local k = d.Name:match("^" .. s .. "_Deck_(%d+)$")
+			if k then
+				slipSegs[s] = slipSegs[s] or {}
+				table.insert(slipSegs[s], { i = tonumber(k), p = d.Position })
+			end
+		end
+		if d.Name:match("^AuxLane_%d+$") then auxSegs += 1 end
+	end
+end
+
+say("BUILT: aux lane segments = " .. auxSegs .. "  (expect ~52 with decel+accel)")
+
+for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+	local g = slipSegs[s]
+	if not g or #g == 0 then
+		say(("BUILT: %s -- NO DECK SEGMENTS (ramp absent)"):format(s))
+	else
+		table.sort(g, function(a, b) return a.i < b.i end)
+		-- How many segments hold deck height before the descent starts?
+		local topY = g[1].p.Y
+		local level = 0
+		for _, seg in ipairs(g) do
+			if math.abs(seg.p.Y - topY) < 0.5 then level += 1 else break end
+		end
+		local drop = topY - g[#g].p.Y
+		say(("BUILT: %s segs=%d  startY=%.1f endY=%.1f drop=%.1f  level-run=%d/%d %s"):format(
+			s, #g, topY, g[#g].p.Y, drop, level, #g,
+			level >= 12 and "<- PARALLEL FIX PRESENT" or "<- OLD DIVING PROFILE"))
+	end
+end
+
+return table.concat(out, "\n")