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_rebuild.luau

@@ -0,0 +1,62 @@
+-- Rebuild the map from current source and report what actually landed.
+-- The workspace snapshot predates today's edits; this regenerates it.
+local SS = game:GetService("ServerScriptService")
+local out = {}
+local function say(s) table.insert(out, s) end
+
+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 return "MapBuilder NOT FOUND" end
+
+local okReq, M = pcall(require, mb)
+if not okReq then return "require failed: " .. tostring(M) end
+
+local old = workspace:FindFirstChild("Map")
+if old then
+	old:Destroy()
+	say("destroyed stale Map")
+end
+
+local t0 = os.clock()
+local okB, err = pcall(function() return M.build() end)
+say(("build: %s  (%.2fs)"):format(okB and "OK" or ("FAILED -> " .. tostring(err)), os.clock() - t0))
+if not okB then return table.concat(out, "\n") end
+
+local map = workspace:FindFirstChild("Map")
+if not map then return table.concat(out, "\n") .. "\nMap MISSING after build" end
+
+local parts, slip, aux = 0, {}, 0
+for _, d in ipairs(map:GetDescendants()) do
+	if d:IsA("BasePart") then
+		parts += 1
+		for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+			local k = d.Name:match("^" .. s .. "_Deck_(%d+)$")
+			if k then
+				slip[s] = slip[s] or {}
+				table.insert(slip[s], { i = tonumber(k), y = d.Position.Y })
+			end
+		end
+		if d.Name:match("^AuxLane_%d+$") then aux += 1 end
+	end
+end
+say(("parts=%d  auxLaneSegs=%d"):format(parts, aux))
+
+for _, s in ipairs({ "PAWestSlip", "PAEastSlip" }) do
+	local g = slip[s]
+	if not g or #g == 0 then
+		say(s .. ": ABSENT")
+	else
+		table.sort(g, function(a, b) return a.i < b.i end)
+		local topY, level = g[1].y, 0
+		for _, seg in ipairs(g) do
+			if math.abs(seg.y - topY) < 0.5 then level += 1 else break end
+		end
+		say(("%s: segs=%d startY=%.1f endY=%.1f level-run=%d/%d %s"):format(
+			s, #g, topY, g[#g].y, level, #g,
+			level >= 12 and "<- PARALLEL ASCENT PRESENT" or "<- old diving profile"))
+	end
+end
+
+return table.concat(out, "\n")