The backers of a proposed ballpark in Richmond’s Shockoe Bottom have not locked up access to a state parking deck on game days, despite a public claim that an agreement is in place. Bryan Bostic, who is working to buy a minor-league baseball team to relocate to Richmond, was asked during a debate last week about the proposed Shockoe Center development whether his group had secured use of the state’s parking deck at 14th and East Main streets.