docs: clarify priceOf stock contract (review)

src/sim/economy.js

@@ -1,6 +1,8 @@
 import { GOODS, BASE_PRICE, TYPICAL_STOCK, MAX_STOCK } from './constants.js';
 
 // Deterministic price curve: scarce -> expensive. Clamped to [0.25x, 4x].
+// Always pass the raw float planet.stock[good]; never reconstruct price from
+// the floored integer stock shown in marketView rows.
 export function priceOf(good, stock) {
   const ratio = TYPICAL_STOCK / Math.max(stock, 1);
   const mult = Math.min(4, Math.max(0.25, ratio));