feat: gc oob should configure beads.role to avoid "warning: beads.role not configured. Run 'bd init' to set."

[csells]

Before you continue

• I searched existing issues and did not find a duplicate.
• I can explain the user problem this solves, not just the implementation I prefer.

Problem to solve

with gc installed oob, creating a bead yields the following error:

warning: beads.role not configured. Run 'bd init' to set.

Proposed change

gc should configure beads oob with a default role that makes sense OR recommend to the user in gc init and gc doctor that they set the bead.role (and how to do so).

Alternatives considered

No response

Scope and impact

No response