Function getRandomCoordinate

getRandomCoordinate(height: number, width: number, size: number): number[][]
Calculates evenly distributed coordinate positions for CAPTCHA characters.

Generates an array of [x, y] coordinates that distribute characters evenly across the canvas width while adding random vertical positioning for security. The coordinates are sorted by x-position to ensure proper left-to-right ordering.
Parameters
- height: number
  Canvas height in pixels
- width: number
  Canvas width in pixels
- size: number
  Number of character positions to generate
Returns number[][]
Array of [x, y] coordinate pairs
Example: Generate positions for 6 characters
```
const positions = getRandomCoordinate(100, 300, 6);
// Returns: [[30, 45], [80, 67], [130, 23], [180, 78], [230, 34], [280, 56]]
```
Example: Use with character drawing
```
const coordinates = getRandomCoordinate(150, 400, 8);
const text = 'SECURITY';

coordinates.forEach(([x, y], index) => {
  ctx.fillText(text[index], x, y);
});
```
- Defined in src/util.ts:83