Adds AlertMatchSpec record (core) and ClickHouseSearchIndex.countExecutionsForAlerting — no FINAL, no text subqueries. Filters by tenant, env, app, route, status, time window, and optional after-cursor. Attributes (JSON string column) use inlined JSONExtractString key literals since ClickHouse JDBC does not bind ? placeholders inside JSON functions. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>