President Joe Biden on Thursday will announce his first raft of executive actions to curb gun violence, including plans to stop the spread of homemade, untraceable firearms known as ghost guns and to tap a prominent gun safety advocate to head the federal agency that regulates the firearm industry, according to senior administration officials. One of the executive actions will give the Justice Department 30 days to publish its proposal to halt the proliferation of ghost guns, which have become increasingly popular among criminals looking to bypass gun laws, according to gun safety activists and law enforcement officials.