feat: add image search and bitmap I/O.

[octalmage]

Summary

Adds the image-search API planned for RobotJS 0.8.0.

• Capture screens and display-specific rectangles as Image objects.
• Load and save BMP images, with opt-in PNG support on macOS and Linux source builds.
• Find, count, and click images using exact or tolerance-based matching.
• Find, count, and read colors inside complete images or bounded search rectangles.
• Convert capture coordinates to screen coordinates, including scaled and negative-origin displays.
• Enumerate displays for multi-monitor capture.
• Preserve the existing Bitmap export as an alias of Image.

API

const robot = require('robotjs');

const screen = robot.screen.capture();
const target = robot.image.load('./target.bmp');
const match = screen.findImage(target, { tolerance: 0.1 });

if (match) {
  screen.click(match, target);
}

Image also provides findImages, countImage, findColor, findColors, countColor, colorAt, save, toScreenPoint, and clickImage.

Verification

• Cross-platform CI covers Linux, macOS, and Windows on Node 24/25.
• PNG-enabled CI runs on Linux and macOS; Windows verifies the disabled path.
• Local image/bitmap/screen suite: 49 specs, 0 failures, 1 expected pending spec.

[octalmage]

I've been testing these changes in a number of end-user software, like https://github.com/octalmage/pixelcolor and so far they're very stable. Still more testing needed but it's looking promising.