refactor: centralize domain values and enforce numeric lint

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

@@ -6,6 +6,9 @@ import {
 
 import type { Money } from '../../../../common/money.types';
 
+const SHARE_PERCENT_DECIMAL_PLACES = 6;
+const PERCENT_SCALED_FACTOR = 100_000_000n;
+
 const categoryTypes = ['STOCK', 'BOND', 'OTHER', 'CASH'] as const;
 
 // Build from positions and cash, never from totals (which already include cash).
@@ -59,10 +62,10 @@ export function portfolioStructure(
                 value:
                   (value.value *
                     10n ** BigInt(total.scale - value.scale) *
-                    100_000_000n +
+                    PERCENT_SCALED_FACTOR +
                     total.value / 2n) /
                   total.value,
-                scale: 6,
+                scale: SHARE_PERCENT_DECIMAL_PLACES,
               })
             : null,
         }));