refactor(shared): update utilities, API layer, and types

src/shared/lib/utils/roundToStepPrecision/roundToStepPrecision.ts

@@ -1,19 +1,25 @@
 import { getDecimalPlaces } from '$shared/lib/utils';
 
 /**
- * Round a value to the precision of the given step
+ * Rounds a value to match the precision of a given step
  *
- * This fixes floating-point precision errors that occur with decimal steps.
- * For example, with step=0.05, adding it repeatedly can produce values like
- * 1.3499999999999999 instead of 1.35.
+ * Fixes floating-point precision errors that occur with decimal arithmetic.
+ * For example, repeatedly adding 0.05 can produce 1.3499999999999999
+ * instead of 1.35 due to IEEE 754 floating-point representation.
  *
- * We use toFixed() to round to the appropriate decimal places instead of
- * Math.round(value / step) * step, which doesn't always work correctly
- * due to floating-point arithmetic errors.
+ * Uses toFixed() instead of Math.round() for correct decimal rounding.
  *
  * @param value - The value to round
- * @param step - The step to round to (defaults to 1)
+ * @param step - The step size to match precision of (default: 1)
  * @returns The rounded value
+ *
+ * @example
+ * ```ts
+ * roundToStepPrecision(1.3499999999999999, 0.05); // 1.35
+ * roundToStepPrecision(1.2345, 0.01); // 1.23
+ * roundToStepPrecision(1.2345, 0.1); // 1.2
+ * roundToStepPrecision(1.5, 1); // 2
+ * ```
  */
 export function roundToStepPrecision(value: number, step: number = 1): number {
     if (step <= 0) {