refactor: 移除 JdbcOperationSupport#queryFirstBoolean 方法

移除了 `JdbcOperationSupport` 中的 `queryFirstBoolean` 静态方法，
统一使用 `queryFirst` 方法配合 `Boolean.class` 进行类型转换。

src/main/java/xyz/zhouxy/jdbc/JdbcOperationSupport.java

@@ -146,21 +146,6 @@ class JdbcOperationSupport {
         return queryFirstInternal(conn, sql, params, (rs, rowNumber) -> rs.getObject(1, clazz));
     }
 
-    /**
-     * 查询第一行第一列并转换为 boolean
-     *
-     * <p>
-     * <b>注：如果查询结果为空，则返回 {@code false}。</b>
-     *
-     * @param conn   数据库连接
-     * @param sql    SQL
-     * @param params 参数
-     */
-    static Boolean queryFirstBoolean(Connection conn, String sql, Object[] params)
-            throws SQLException {
-        return queryFirst(conn, sql, params, (rs, rowNumber) -> rs.getBoolean(1));
-    }
-
     // #endregion
 
     // #region - update & batchUpdate

src/main/java/xyz/zhouxy/jdbc/SimpleJdbcTemplate.java

@@ -133,7 +133,7 @@ public class SimpleJdbcTemplate implements JdbcOperations {
             throws SQLException {
         try (Connection conn = this.dataSource.getConnection()) {
             final Boolean result = JdbcOperationSupport
-                    .queryFirstBoolean(conn, sql, params);
+                    .queryFirst(conn, sql, params, Boolean.class);
             return Boolean.TRUE.equals(result);
         }
     }
@@ -339,7 +339,8 @@ public class SimpleJdbcTemplate implements JdbcOperations {
         @Override
         public boolean queryBoolean(String sql, Object[] params)
                 throws SQLException {
-            final Boolean result = JdbcOperationSupport.queryFirstBoolean(this.conn, sql, params);
+            final Boolean result = JdbcOperationSupport
+                    .queryFirst(this.conn, sql, params, Boolean.class);
             return Boolean.TRUE.equals(result);
         }