Provide a way to define per org categories and descriptions so that the agent classifies posts using my organization’s taxonomy

[mjfusa]

Acceptance Criteria

Admin can define custom categories (e.g., “Critical”, “Low Impact”, “Requires Training”, “Security-Related”).
Admin can supply category descriptions or examples.
The agent uses these categories for classification.
The agent returns:

Selected category
A justification explaining why this category was applied

The agent handles categories stored in:

GitHub config (JSON/YAML), or
SharePoint list, or
Dataverse table (future option)