“How’s our unity event gonna compete with this!?” I’d lamented on the No. 5 train reading that combined presidential campaign spending topped $1 billion for partisan advertising, transportation polling and something called “ground game.” “Our budget’s 500 — bucks, not millions!” Promoting a screening of anti-polarization documentary “Undivide Us” at Brooklyn’s Plymouth Church, my “ground game” was pedaling a Citi Bike tying flyers to wrought iron fences. “Thank God God’s on our side,” joked a co-sponsor. “Pray for loaves, fishes and a bargain sound engineer,” I’d laughed.