motion_vs_gsap

feat: implement dynamic scroll-linked header height and position for motion and gsap recipes

feat: enable Fixed Header recipe in motion and gsap navigation lists and reformat templates

refactor: rewrite GSAP step animation logic with dedicated handlers for checkmark and number transitions

feat: implement animated email client list transitions in motion and gsap pages

refactor: reformat codebase indentation and comment out unused exercise entries in the motion index page