Function mrzCharValue

Public algorithm primitives. Tree-shakable subpath: nationid/algorithms.

Each function is a pure mathematical primitive with cited spec.

mrzCharValue(ch: string): number
Char value for MRZ checksum: '0'-'9' → 0..9; 'A'-'Z' → 10..35; '<' → 0.

Returns -1 for any character outside the MRZ alphabet (callers may treat this as "invalid" without an exception).
Parameters
- ch: string
  A single-character string. Multi-char strings return -1.
Returns number
Numeric value in [0, 35], or -1 for invalid input.
Example
```
import { mrzCharValue } from "nationid/algorithms";

mrzCharValue("A"); // 10
mrzCharValue("Z"); // 35
mrzCharValue("<"); // 0
mrzCharValue("a"); // -1  (lowercase not allowed)
```
- Defined in algorithms/icao-9303.ts:40