### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### The Feature

LiteLLM currently supports virtual keys, users, teams, organizations, projects, budgets, and metadata. However, enterprise deployments often need a set of first-class business ownership fields that can consistently participate in authorization, spend attribution, routing, UI filtering, and reporting.

I would like LiteLLM to support enterprise metadata fields on virtual keys, users, teams, and related usage records, such as:

- `business_group` - `department` - `employee_id` - `cost_center` - `dedicated_budget_limit` - `group_priority`

Desired behavior:

1. Allow these fields to be set when creating or updating virtual keys. 2. Preserve these fields in LiteLLM's DB records and standard logging objects. 3. Expose these fields in Admin UI key/user/team tables and filters. 4. Allow usage/spend reports to group and filter by these fields. 5. Make these fields available to custom callbacks and routing logic. 6. Optionally allow admins to define allowed values for fields like `business_group` and `department`.

Example API payload:

```json { "key_al…