fix: count brokerage cash once and skip short-position return percent (WealthLedger/backend#140)

src/modules/investments/portfolio/domain/portfolio-structure.ts

@@ -43,6 +43,8 @@ export function portfolioStructure(
     currencies.set(money.currency, group);
   };
   for (const position of positions) {
+    // CURRENCY positions mirror cash, which is counted once as CASH below.
+    if (position.type === 'CURRENCY') continue;
     const type = ['BOND', 'STOCK'].includes(position.type)
       ? position.type
       : 'OTHER';