Rewrite onboarding prose to a neutral voice

scripts/doctor.sh

@@ -110,7 +110,7 @@ if command -v xdg-open >/dev/null 2>&1 || command -v open >/dev/null 2>&1; then
     printf '  %s %-12s -> (detected)\n' "$(_fc_tag "$_FC_GREEN" ok)" 'web browser'
 else
     printf '  %s %-12s -> no xdg-open/open on PATH.\n' "$(_fc_tag "$_FC_YELLOW" warn)" 'web browser'
-    printf '         if this is a headless machine, run: just login-headless\n'
+    printf '         headless mode: just login-headless\n'
     case "$pm" in
         apt)    printf '         otherwise install:  sudo apt-get install -y xdg-utils\n' ;;
         dnf)    printf '         otherwise install:  sudo dnf install -y xdg-utils\n' ;;
@@ -214,7 +214,7 @@ if [ "$missing" -gt 0 ]; then
         printf '    %s\n' "$c"
     done
     printf '\n'
-    warn 'then re-run: just doctor'
+    warn 're-run: just doctor'
     exit 1
 fi