List intel incidents

Lists deduplicated, scored ontology incidents linked from the OSINT cache. Filters by category, severity, status, or last-observed lower bound. Required scopes vary by `category` filter: - `category=cyber` → `intel:cyber` or `intel:explorer` - any other category → `intel:finint` or `intel:explorer` - no `category` filter → `intel:explorer` Supports x402 pay-per-request. Requests without `Authorization` return `402 Payment Required` with payment requirements; retry with a signed `PAYMENT-SIGNATURE` header.