Rename screw tubes to screw conveyors (t44)

Player text says Screw conveyor; code uses screw (BP_SCREW, piece id
screw, screwIntake...). No compatibility code for old saves or
blueprints. Suite outputs match before and after apart from names.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/sim/world.js

@@ -17,7 +17,7 @@ let awake, hot, hotLvl, powderArea, roofDirty;
 let loadWakeOrder = null, loadWakePending = null, loadWakeIndex = 0;
 let tick = 0, tickStamp = 1;
 let machines = [null], molds = [], nets = [null], pcells = new Set(), powerDirty = true;
-let beltL = [], beltR = [], tubeLists = Array.from({ length: IS_TUBE.length }, () => []);
+let beltL = [], beltR = [], screwLists = Array.from({ length: IS_SCREW.length }, () => []);
 let brokenMachines = [];
 let ghostMachines = [], ghostBlocked = new Set();
 const EV = [];
@@ -55,7 +55,7 @@ function alloc(w, h) {
   roofDirty = new Uint8Array(CW).fill(1);
   powderArea = new Uint8Array(NCH).fill(1); // unknown areas get one visit before being ruled out
   machines = [null]; molds = []; nets = [null]; pcells = new Set(); powerDirty = true;
-  beltL = []; beltR = []; tubeLists = Array.from({ length: IS_TUBE.length }, () => []); brokenMachines = [];
+  beltL = []; beltR = []; screwLists = Array.from({ length: IS_SCREW.length }, () => []); brokenMachines = [];
   ghostMachines = []; ghostBlocked = new Set();
   tick = 0; tickStamp = 1; drillPulses = []; lastPulseTick = -99; undoStack = []; undoRec = null;
   pipeNets = []; pipeNetAt = null; pipesDirty = true;