fix(tui): renderer: replace tabs with spaces in plain content

We need to ensure that tabs in plain text content are replaced with
spaces otherwise they will be escaped and displayed as tab unicode
picture characters.

internal/tui/components/chat/messages/renderer.go

@@ -656,6 +656,7 @@ func joinHeaderBody(header, body string) string {
 func renderPlainContent(v *toolCallCmp, content string) string {
 	t := styles.CurrentTheme()
 	content = strings.ReplaceAll(content, "\r\n", "\n") // Normalize line endings
+	content = strings.ReplaceAll(content, "\t", "    ") // Replace tabs with spaces
 	content = strings.TrimSpace(content)
 	lines := strings.Split(content, "\n")