feat: implement percentage calculation utility and refactor analytics to use it

- Added `calcPercentageWithRounding` function for consistent percentage calculations with rounding.
- Updated course and user analytics to utilize the new utility for progress and average grade calculations.
- Removed redundant rounding logic from analytics functions.

apps/dashboard/src/lib/utils/functions/number.ts

@@ -0,0 +1,10 @@
+export function calcPercentageWithRounding(a: number, b: number) {
+  if (b === 0) {
+    return 0;
+  }
+  const rawPercentage = (a / b) * 100;
+  const fixedString = rawPercentage.toFixed(1);
+  const roundedNumber = parseFloat(fixedString);
+
+  return isNaN(roundedNumber) ? 0 : roundedNumber;
+}