Function mod11WeightedSum

mod11WeightedSum(digits: string, weights: readonly number[]): number
Compute weighted sum mod 11, given digits and weights.

Weights are applied 1-to-1 with digits from left to right. If weights is shorter than digits, an error is thrown — country-specific code must pre-extend or cycle weights as needed.

Returns the raw sum (NOT yet mod 11). Country-specific code typically applies 11 - (sum % 11) and maps the special cases (0 / 10 / 11) per its own variant.
Parameters
- digits: string
  Digit-only string. Each char must be '0'..'9'.
- weights: readonly number[]
  Array of integer weights with weights.length === digits.length.
Returns number
The raw weighted sum (not yet reduced).
Throws
if digits and weights differ in length, or if digits contains a non-digit character.
Example
```
import { mod11WeightedSum } from "nationid/algorithms";

// BR CPF first check-digit weights are [10,9,8,7,6,5,4,3,2]
const sum = mod11WeightedSum("111444777", [10,9,8,7,6,5,4,3,2]);
const checkDigit = ((sum * 10) % 11) % 10; // CPF-specific reduction
```
- Defined in algorithms/mod11.ts:43