No rock festival? No problem. Just throw your own! That’s what Jersey City’s Royal Blush will do on Saturday, March 2, when the local dream-pop quintet headlines “Blush Fest,” a free all-day showcase at 902 Brewing Co. The event features nine bands from New Jersey and beyond and will run from 1 to 10 p.m. Royal Blush won’t be releasing a new album for a while, and it’s not an anniversary. So why a festival? Royal Blush has a simple answer: Why not? “I guess the celebration is just for Jersey music,” said Allison Heckart, the band’s lead singer. “We hadn’t done a Jersey show in a while and towa…