Function checkValidRuku

checkValidRuku(x: unknown): asserts x is Ruku
Type guard that checks if a value is a valid Ruku number.
Parameters
- x: unknown
  The value to check
Returns asserts x is Ruku
Throws
If the value is not an integer number

Throws
If the number is not within valid Ruku range
Example
```
checkValidRuku(5); // OK
checkValidRuku("5"); // Throws TypeError
checkValidRuku(999); // Throws RangeError
```
- Defined in validation.ts:117