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/cells.js

@@ -59,9 +59,12 @@ function enter(m, ph, j, dx, dy) {
 }
 
 // ---------- Movement ----------
-// Heavy grains settle through a loose pile of much lighter ones, slowly. A sorting
+// Heavy grains settle through a loose pile of much lighter ones. A sorting
 // step keeps its area awake for a while so a pile finishes sorting even at rest.
-let SORTP = 0.003;
+// Through burning fuel it stays slow: a furnace bed is tuned to it, and dirt heaped on a burning
+// pile has to smother it into charcoal, not sink through.
+let SORTP = 0.06;
+const SORTP_FUEL = 0.003;
 // Liquids step up to LSTEP cells toward a drop in one tick (fewer the thicker they are), and a top-layer grain looks LFILM
 // times as far for one (a two-times range strands the far end of a 200-grain-wide ledge).
 // World generation settles with both at 1, so every seed keeps making the same world.
@@ -73,7 +76,7 @@ function powder(i, x, y, m) {
   // a grain at least twice as dense works its way down through a loose pile. Unlit fuel
   // packs too tight for that, so a mixed furnace charge stays mixed until the fire gets in.
   const t = mat[b];
-  if (PH[t] === PH_POWDER && DENS[m] >= DENS[t] * 2 && (!FUEL[t] || (flags[b] & F_BURN)) && stamp[b] !== tickStamp && !occ[b] && part[b] !== P_GRATE && part[b] !== P_FILTER && rnd() < SORTP) { move(i, b, x, y, x, y + 1); awake[(y >> 5) * CW + (x >> 5)] = 40; return; }
+  if (PH[t] === PH_POWDER && DENS[m] >= DENS[t] * 2 && (!FUEL[t] || (flags[b] & F_BURN)) && stamp[b] !== tickStamp && !occ[b] && part[b] !== P_GRATE && part[b] !== P_FILTER && rnd() < (FUEL[t] ? SORTP_FUEL : SORTP)) { move(i, b, x, y, x, y + 1); awake[(y >> 5) * CW + (x >> 5)] = 40; return; }
   // a grain lying right on a belt or filter is held by it: the surface carries it, it does not slide off the edge
   if (t === BELTL || t === BELTR || part[b] === P_FILTER) return;
   if (rnd() < STICK[m]) {
@@ -158,11 +161,23 @@ function gas(i, x, y, m) {
     if (nx >= 0 && nx < W && mat[i + d] === EMPTY && passable(m, PH_GAS, i + d, d, 0)) { move(i, i + d, x, y, nx, y); }
   }
 }
+function wakeBotPowder() {
+  const x = bot.x + bot.w / 2, y = bot.y + bot.h / 2;
+  const x0 = Math.max(0, Math.floor((x - 100) / 32)), x1 = Math.min(CW - 1, Math.floor((x + 100) / 32));
+  const y0 = Math.max(0, Math.floor((y - 100) / 32)), y1 = Math.min(CH - 1, Math.floor((y + 100) / 32));
+  for (let cy = y0; cy <= y1; cy++) for (let cx = x0; cx <= x1; cx++) {
+    const c = cy * CW + cx;
+    if (!powderArea[c] || awake[c]) continue;
+    const dx = Math.max(cx * 32 - x, 0, x - (cx * 32 + 31));
+    const dy = Math.max(cy * 32 - y, 0, y - (cy * 32 + 31));
+    if (dx * dx + dy * dy <= 10000) awake[c] = 1;
+  }
+}
 function simMove() {
   for (let cy = CH - 1; cy >= 0; cy--) {
     const rowBase = cy * CW;
     let any = false;
-    for (let cx = 0; cx < CW; cx++) if (awake[rowBase + cx]) { any = true; break; }
+    for (let cx = 0; cx < CW; cx++) if (awake[rowBase + cx]) { any = true; powderArea[rowBase + cx] = 0; }
     if (!any) continue;
     const y0 = cy << 5, y1 = Math.min(H, y0 + 32);
     for (let y = y1 - 1; y >= y0; y--) {
@@ -176,8 +191,10 @@ function simMove() {
         const dx = ltr ? 1 : -1, xEnd = ltr ? x1 : x0 - 1;
         for (let x = ltr ? x0 : x1 - 1; x !== xEnd; x += dx) {
           const i = yw + x, m = mat[i];
-          if (m === EMPTY || stamp[i] === tickStamp) continue;
+          if (m === EMPTY) continue;
           const ph = PH[m];
+          if (ph === PH_POWDER) powderArea[rowBase + cx] = 1;
+          if (stamp[i] === tickStamp) continue;
           if (ph === PH_SOLID) continue;
           const p = part[i];
           if (p >= P_TU && p <= P_TR && ph === PH_POWDER) continue; // a screw tube moves its own grains