- instructors: remove Outfit display font, use Inter for headers like
all other sites. Remove redundant @import and h1-h4 font override.
- mlsysim: replace site-specific logo.svg with ecosystem shield logo
- tinytorch: replace TinyTorch-specific logo with ecosystem shield logo
All Quarto sites now have identical navbar: same shield logo, same Inter
font stack, same dark mode toggle, same shared responsive behavior.
