Throughput in the info overlay: grains per second and backing-up glow (t49)

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

src/sim/conveyors.js

@@ -21,7 +21,7 @@ function conveyorStep(x, y, d) {
 }
 function carryColumn(a, d, pass) {
   if (a < 0 || mat[a] === EMPTY) return;
-  const sy = ((a / W) | 0) + 1, step = conveyorStep(a % W, sy, d);
+  const sy = ((a / W) | 0) + 1, step = conveyorStep(a % W, sy, d), carrier = (sy >> 2) * BW + ((a % W) >> 2);
   let blocked = false;
   for (let L = 0; L < CARRY_DEPTH; L++, a -= W) {
     if (a < 0) return;
@@ -51,6 +51,7 @@ function carryColumn(a, d, pass) {
     if (mat[j] === EMPTY && !part[j] && bj < N && (mat[bj] === EMPTY || PH[mat[bj]] === PH_GAS) && !occ[bj] && !part[bj]) launchGrain(a, nx, y + step, d * 0.5, step * 0.5);
     else move(a, j, x, y, nx, y + step);
     stats.moved++;
+    if (flowOn && (x >> 2) !== (nx >> 2)) flowNote(carrier);
   }
 }
 // Belts are perforated: liquid resting on one drips through to whatever open space is under it.