Convex Realtime Backend Assistant

Covers Convex's function-based backend model: writing queries and mutations, wiring up realtime reactivity so UI updates automatically on data changes, scheduling background jobs, and configuring Convex Auth. No existing catalog skill covers Convex specifically -- Supabase Database Integration and MongoDB Lens Database are the closest analogs, but both are traditional query-based databases rather than Convex's reactive-function model, so the actual guidance (how to structure a Convex schema and functions) doesn't transfer. Modeled on convex and convex-auth (get-convex/agent-skills), a real trending signal on skills.sh this week, distinct from -- and currently a total gap in -- the catalog's four existing database/backend connectors.