Ingot molds drop bars out of the bottom on their own

Bars no longer get thrown up into the furnace, and F is no longer needed to
collect them. Blocked bars wait in the trough; the short stub stays for the
next firing; F is optional upkeep (clean, chip slag, rake).

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

src/sim/pieces.js

@@ -72,7 +72,7 @@ const PIECES = [
   { id: 'dock', name: 'Trade dock', kind: 'machine', bw: 6, bh: 4, cost: [], hidden: true, fixed: true,
     desc: 'Owned by the claim office. Anything that drops through the grate in its floor is sold on the spot. Build walls around it to funnel more in.' },
   { id: 'ingotmold', name: 'Ingot mold', kind: 'mold', mold: 'ingot', variants: 'wall',
-    desc: 'A long trough. Pour molten metal in, let it set, press F: it snaps into bars of 8 grains, up to 3.' },
+    desc: 'A long trough. Pour molten metal in: bars of 8 grains drop out of the bottom when set, up to 3. Leave one open block below it; a belt under that carries them off. F cleans the trough, chips off slag and rakes the furnace grate.' },
   { id: 'bitmold', name: 'Bit mold', kind: 'mold', mold: 'bit', variants: 'wall',
     desc: 'A drill-bit-shaped cavity. Cast a harder metal in it to upgrade your drill.' },
   { id: 'tankmold', name: 'Tank mold', kind: 'mold', mold: 'tank', variants: 'wall',
@@ -86,8 +86,7 @@ const WHEEL_K = 0.32, ENGINE_K = 40;
 
 const MOLDS = {
   ingot: {
-    // one long trough: metal runs along it and sets level; knocking it out
-    // snaps the ingot into bars of 8 grains each
+    // one long trough: metal sets level and drops bars of 8 grains below
     name: 'Ingot mold', rows: [
       '................',
       '#oooooooooooooo#',