Piles near the bot sort, and 20 times faster; burning fuel keeps the slow pace (t21)

- SORTP 0.003 -> 0.06: ore sinks through 8 rows of ash in about 7 s near the bot.
- wakeBotPowder(): every 8 ticks, areas with loose grains within 100 grains of the bot get a
  sorting chance; far away, resting piles still sleep.
- Sinking through burning fuel stays at 0.003, so buried burning piles still char and furnace
  beds behave as tuned. World generation settles at the old rate: seeds are unchanged.

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

src/sim/world.js

@@ -13,7 +13,7 @@ let ents = []; // loose objects (bars)
 let bgm; // background layer: trees. Liquids, powders and gases pass in front of it.
 let flyers = []; // grains in flight, blown out of the bot
 let ghostBlocks = new Map(), ghostMolds = [];
-let awake, hot, hotLvl;
+let awake, hot, hotLvl, powderArea;
 let tick = 0, tickStamp = 1;
 let machines = [null], molds = [], nets = [null], pcells = new Set(), powerDirty = true;
 let beltL = [], beltR = [], tubeLists = [[], [], [], [], []];
@@ -50,6 +50,7 @@ function alloc(w, h) {
   surfY = new Int16Array(w); roofY = new Int16Array(w); dirtY = new Int16Array(w); graniteY = new Int16Array(w); basaltY = new Int16Array(w); magmaY = new Int16Array(w);
   AMB = new Float32Array(h);
   awake = new Uint8Array(NCH); hot = new Uint8Array(NCH); hotLvl = new Uint8Array(NCH);
+  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 = [[], [], [], [], []]; brokenMachines = [];
   ghostMachines = []; ghostBlocked = new Set();