Add new `minimal` config option that provides a cleaner, more focused
color scheme with fewer distinct colors:
- Variables/constants: white
- Functions/methods: blue
- Types: aqua
- Keywords/statements: gray
- Operators: yellow
- Brackets/punctuation: gray
- Properties/members: violet
Replace the negative boolean `disableItalics` with positive `italics` option for better API ergonomics. This affects all italic styling throughout the theme including comments, keywords, and plugin highlights.
BREAKING CHANGE: Users must update their configuration from `disableItalics = true` to `italics = false`.
