Hollywood's favorite parlor game this week isn't a box office pool — it's watching Supergirl wobble toward Friday's release like a fighter who took one too many jabs before the bell. The second live-action entry in James Gunn's DCU arrives June 26 backed by a record-breaking $100M+ promotional campaign (80 sponsors, including Ulta Beauty, KFC, and Samsung) but tracking that's cratering toward a $39–55 million domestic opening — less than half of Superman's $125M...