ANSI color swatches display (litmus-g6c0)
Display the 16 ANSI colors + fg/bg/cursor/selection as colored blocks in the terminal.
Summary of Changes
Implemented ANSI color swatches TUI display using ratatui and crossterm. Added ThemeWithExtras wrapper with hardcoded Tokyo Night theme. SwatchesWidget renders 2x8 grid with labels plus fg/bg/cursor/sel row. main.rs bootstraps TUI with clean terminal restore on quit.