Categories/families can now be registered at runtime, not just the hardcoded
ALERT_CATEGORIES/VALID_TOGGLES. A generic data source registers its category
as a first-class family with its own (default-disabled) toggle, so its events
resolve to that family instead of being dropped as "other" or buried in
mesh_health — it becomes routable. Existing families/categories unchanged.
Phase A of making custom sources first-class feeds.
Co-authored-by: Matt Johnson <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
