Enrich product category pages and show Brent and gas oil rates.

Expand each category with body copy, highlights, supply steps, and FAQ in fa/en/ar, and surface livedata oil benchmarks on the oil page.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/market/displayed.ts

@@ -16,6 +16,7 @@ import type { InstrumentId } from "./instruments";
  */
 export const displayed: InstrumentId[] = [
   "400106", // نفت برنت
+  "400506", // گازوئیل
   "200103", // دلار تتر
   "200101", // دلار - صرافی
   "200201", // یورو - صرافی

src/lib/market/instruments.ts

@@ -17,6 +17,7 @@ export const instruments = {
   "300306": { fa: "پلاتین" },
   "400106": { fa: "نفت برنت" },
   "400206": { fa: "نفت سبک آمریکا" },
+  "400506": { fa: "گازوئیل" },
   "6001": { fa: "بورس تهران" },
   "600206": { fa: "داوجونز" },
   "600306": { fa: "اس اند پی" },
@@ -52,5 +53,5 @@ export const instruments = {
 export type InstrumentId = keyof typeof instruments;
 
 /* Also published but unlabelled upstream, so left out until identified:
-   300406, 300606, 300706, 300806, 300906, 301006, 301106, 400306, 400406, 400506, 500106, 500206, 500306, 500407, 500607, 500706, 500806, 500907
+   300406, 300606, 300706, 300806, 300906, 301006, 301106, 400306, 400406, 500106, 500206, 500306, 500407, 500607, 500706, 500806, 500907
 */