Constant CREATE_UPDATE_LOG_TABLE 

pub const CREATE_UPDATE_LOG_TABLE: &str = r#"
    CREATE TABLE IF NOT EXISTS update_log (
        id         INTEGER PRIMARY KEY AUTOINCREMENT,
        memory_id  INTEGER NOT NULL,
        action     TEXT    NOT NULL,
        old_hash   TEXT    NOT NULL,
        new_hash   TEXT    NOT NULL,
        reason     TEXT    NOT NULL DEFAULT '',
        timestamp  TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
    );
    CREATE INDEX IF NOT EXISTS idx_update_log_memory ON update_log(memory_id);
"#;

DDL for the update_log table.

Call once during schema setup (e.g., alongside CREATE_FACTS_TABLE).