[FEAT] Auto theme should work with colorblind-friendly palettes

I'm colorblind and use the daltonized theme. The new auto option in v2.1.111 throws away the colorblind-friendly palette, so I can't use it.

auto is a sibling of the daltonized and ANSI variants, not a modifier that composes with them. Either I get ambient switching (standard palette only) or the daltonized palette (no switching). Not both.

The daltonized themes exist because Claude Code treats colorblind users as a first-class audience. Leaving that audience out of the auto rollout undoes some of that work. The canonical tracking issue (#2990) was opened in an accessibility context and is still open.

Proposed fix

The existing detection path already works. Only the palette selection needs a parameter. Two shapes:

1. New enum values: auto-daltonized, auto-ansi. Smallest diff.
2. Modifier config: { theme: "auto", palette: "daltonized" }. Cleaner, breaking.

I'd love to switch to auto but can't until the daltonized palettes are supported. Happy to test.

Environment

• Claude Code 2.1.112
• "theme": "dark-daltonized" in ~/.claude.json
• Related: #2990, #11813, #1076