feat: auto-detect non-TTY and adjust output (bd-xrwy)

Add TTY detection to automatically disable ANSI colors when stdout is
piped or redirected. Respects standard conventions:
- NO_COLOR environment variable (no-color.org)
- CLICOLOR=0 disables color
- CLICOLOR_FORCE enables color even in non-TTY

Also adds ShouldUseEmoji() helper controlled by BD_NO_EMOJI.
Pager already disabled non-TTY in previous work (bd-jdz3).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

internal/ui/styles.go

@@ -7,8 +7,16 @@ import (
 	"strings"
 
 	"github.com/charmbracelet/lipgloss"
+	"github.com/muesli/termenv"
 )
 
+func init() {
+	// Disable colors when not appropriate (non-TTY, NO_COLOR, etc.)
+	if !ShouldUseColor() {
+		lipgloss.SetColorProfile(termenv.Ascii)
+	}
+}
+
 // Ayu theme color palette
 // Dark: https://terminalcolors.com/themes/ayu/dark/
 // Light: https://terminalcolors.com/themes/ayu/light/