Agent Skills: searchable-events

The NIP-50 indexing surface of Quartz — the `SearchableEvent` interface, which event kinds are searchable, exactly what text each kind's `indexableContent()` contributes, how the SQLite/filesystem stores consume it, and the NIP-50 `SearchQuery` extension grammar plus `SearchRelayListEvent` (kind 10007). Use when making a kind searchable, changing what a kind indexes, diffing the searchable set at a Quartz version bump (external search engines mirror this table), debugging why an event is or isn't found by search, or working with search extensions (`include:spam`, `domain:`, …).