[bug] init role prompt accepts 1,3 but keeps only the first role #759

Description

The interactive role prompt in teamai init parses a comma list, and its error text asks for "one or more role numbers, separated by commas". init then keeps only the first number and saves additionalRoles: []. Entering 1,3 sets role 1 and drops role 3 without a warning.

parseRoleSelection("1,3")                     [1, 3]   src/init.ts:45
const [primaryIndex] = ...                    1        src/init.ts:117
return { primaryRole, additionalRoles: [] }            src/init.ts:124

Additional roles can only be set later, with teamai roles set <primary> --add <roles...>.

Suggested fix

Accept a single number at the primary role prompt, and point to roles set --add for the rest. Keeping the extra numbers as additionalRoles would also work, but it changes what init installs.

Related: #757, where a project prompt would parse the same kind of list.