Case-Sensitive Text Captcha

I’m ready to add a simple, effective defence against bots on my site and need a developer to build a custom, case-sensitive text captcha. The challenge text should be visually protected by smooth wavy-line distortion so humans can still read it at a glance while automated scripts struggle. Here’s what I expect: a compact module (plain PHP, Python, or JavaScript—whichever you’re most comfortable with) that generates the image on the fly, validates the visitor’s input on form submit, and lets me tweak essentials such as character length, font family, colour palette, and distortion strength through a few easy constants or settings. The code has to slot neatly into an existing page without extra frameworks, and I should be able to drop it on multiple forms after a single include. Please package the finished script, a quick integration guide, and a short README explaining any external libraries or GD/ImageMagick calls you use. A demo page that proves generation and validation are working will complete the hand-off.