Bootstrapping the local DynamoDB tables

A split terminal shows the game stack still running in the top pane (DynamoDB Local and the Vite client on localhost:5173). In the bottom pane, the bootstrap commands run and create each DynamoDB table in turn, printing table details (billing mode, attribute definitions, and key schema) followed by "Created table" for tables including "Usernames" and "Persona." It finishes with "Local DynamoDB bootstrap complete!"