Per-component Slots lines repeated 71 bytes of identical boilerplate
explaining the Vec<String>-of-IDs convention. Adding MediaCardGrid in
Phase 180 pushed prompt() 23 bytes over the 10 KB budget (CONTEXT D-17).

Declare the slot convention once in the catalog preamble; per-component
Slots lines now list field names only. Saves ~200 bytes, restores
headroom under the budget, and removes redundant per-section noise.