Add protanopia- and tritanopia-safe Vim variants

[bruschill]

What

Adds two colorblind-safe Vim colorschemes derived from the canonical vim/colors/madeofcode.vim, plus README documentation.

• vim/colors/madeofcode-protan.vim — protanopia (red-blindness). The signature red keywords render as a near-invisible gray to protanopes, so they move to bright amber, and syntax roles are re-encoded onto the blue↔yellow axis + lightness (the channels protanopes retain).
• vim/colors/madeofcode-tritan.vim — tritanopia (blue-blindness). Red, green, and magenta survive this deficiency and are kept; the blue family (which otherwise collapses into a single teal) is rotated onto pink / orange / teal.

How

Both variants are generated by remapping the source palette hex-for-hex, so every highlight group stays consistent with the canonical scheme. The remaps were chosen and re-verified against Machado 2009 dichromat simulation to confirm previously-colliding syntax roles now separate. ctermfg codes were recomputed to the nearest xterm-256 color for each remapped hue so the variants also render correctly in 256-color terminals.

Docs

• Vim section gains a Colorblind-safe variants subsection with install notes.
• New Accessibility subsection in the color breakdown with before/after swatch tables for each variant.
• Contents updated with links to both.

Notes / caveats

With only blue↔yellow + lightness available, protanopia genuinely can't give all 9 roles unique hues — String/Identifier lean on lightness and Comment keeps its italic. The tightest remaining tritan pair is Constant (pink) vs Decorator (orange). Documented honestly rather than over-claimed.