fix: refactor asciifont and fix seg fault on color setters

[msmps]

Summary

Refactors ASCIIFont to use color and backgroundColor properties instead of fg/bg, and updates examples and documentation.

Changes

• API Refactor: ASCIIFont now accepts ColorInput | ColorInput[] for color and ColorInput for backgroundColor
• Removed properties: fg and bg options removed from ASCIIFontOptions
• Updated examples: All ASCII font examples migrated to new API
• Documentation: Added missing <textarea> and <code> components to README

Breaking Changes

• fg and bg properties removed - use color and backgroundColor instead
• Color parsing handled internally - pass ColorInput types (string, RGBA, etc.) directly