feat(cli): add zero-dependency ANSI styling

Replaces lipgloss with ~100 lines of owned code.
Supports bold, dim, italic, underline, RGB/hex colors.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkg/cli/ansi.go

@@ -0,0 +1,123 @@
+package cli
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// ANSI escape codes
+const (
+	ansiReset     = "\033[0m"
+	ansiBold      = "\033[1m"
+	ansiDim       = "\033[2m"
+	ansiItalic    = "\033[3m"
+	ansiUnderline = "\033[4m"
+)
+
+// AnsiStyle represents terminal text styling.
+// Use NewStyle() to create, chain methods, call Render().
+type AnsiStyle struct {
+	bold      bool
+	dim       bool
+	italic    bool
+	underline bool
+	fg        string
+	bg        string
+}
+
+// NewStyle creates a new empty style.
+func NewStyle() *AnsiStyle {
+	return &AnsiStyle{}
+}
+
+// Bold enables bold text.
+func (s *AnsiStyle) Bold() *AnsiStyle {
+	s.bold = true
+	return s
+}
+
+// Dim enables dim text.
+func (s *AnsiStyle) Dim() *AnsiStyle {
+	s.dim = true
+	return s
+}
+
+// Italic enables italic text.
+func (s *AnsiStyle) Italic() *AnsiStyle {
+	s.italic = true
+	return s
+}
+
+// Underline enables underlined text.
+func (s *AnsiStyle) Underline() *AnsiStyle {
+	s.underline = true
+	return s
+}
+
+// Foreground sets foreground color from hex string.
+func (s *AnsiStyle) Foreground(hex string) *AnsiStyle {
+	s.fg = fgColorHex(hex)
+	return s
+}
+
+// Background sets background color from hex string.
+func (s *AnsiStyle) Background(hex string) *AnsiStyle {
+	s.bg = bgColorHex(hex)
+	return s
+}
+
+// Render applies the style to text.
+func (s *AnsiStyle) Render(text string) string {
+	if s == nil {
+		return text
+	}
+
+	var codes []string
+	if s.bold {
+		codes = append(codes, ansiBold)
+	}
+	if s.dim {
+		codes = append(codes, ansiDim)
+	}
+	if s.italic {
+		codes = append(codes, ansiItalic)
+	}
+	if s.underline {
+		codes = append(codes, ansiUnderline)
+	}
+	if s.fg != "" {
+		codes = append(codes, s.fg)
+	}
+	if s.bg != "" {
+		codes = append(codes, s.bg)
+	}
+
+	if len(codes) == 0 {
+		return text
+	}
+
+	return strings.Join(codes, "") + text + ansiReset
+}
+
+// Hex color support
+func fgColorHex(hex string) string {
+	r, g, b := hexToRGB(hex)
+	return fmt.Sprintf("\033[38;2;%d;%d;%dm", r, g, b)
+}
+
+func bgColorHex(hex string) string {
+	r, g, b := hexToRGB(hex)
+	return fmt.Sprintf("\033[48;2;%d;%d;%dm", r, g, b)
+}
+
+func hexToRGB(hex string) (int, int, int) {
+	hex = strings.TrimPrefix(hex, "#")
+	if len(hex) != 6 {
+		return 255, 255, 255
+	}
+	r, _ := strconv.ParseInt(hex[0:2], 16, 64)
+	g, _ := strconv.ParseInt(hex[2:4], 16, 64)
+	b, _ := strconv.ParseInt(hex[4:6], 16, 64)
+	return int(r), int(g), int(b)
+}