Function countDecimals

countDecimals(input: string): number
Counts the number of decimal places in a numeric string.
Parameters
- input: string
  The string representation of a number.
Returns number
The number of decimal places. Returns 0 if there are no decimal places.
Example
```
countDecimals('123.456'); // Returns 3
countDecimals('123');     // Returns 0
```