Function cmd_adopt 

pub fn cmd_adopt(
    beans_dir: &Path,
    parent_id: &str,
    child_ids: &[String],
) -> Result<HashMap<String, String>>

Adopt existing beans as children of a parent bean.

This command:

1. Validates that the parent bean exists
2. For each child ID:
   • Loads the bean
   • Assigns a new ID: {parent_id}.{N} (where N is sequential)
   • Sets the bean’s parent field to parent_id
   • Renames the file to match the new ID
3. Updates all dependency references across ALL beans
4. Rebuilds the index

Arguments

• beans_dir - Path to the .beans/ directory
• parent_id - The ID of the parent bean
• child_ids - List of bean IDs to adopt as children

Returns

A map of old_id -> new_id for the adopted beans