fix: resolve PHPUnit failures from M4 remediation commit

- tests/bootstrap.php: add PRAUTOBLOGGER_DEFAULT_BOARD_COLUMN_LIMIT (20)
  so unit tests can reference the constant used by the new settings-backed
  LIMIT in class-board-gen-log-query.php and class-board-data-provider.php.

- tests/unit/Admin/BoardGenLogQueryTest.php: restructure to use make_wpdb()
  helper that builds a fresh mock per test, so tests that need non-empty
  get_results() rows can pass their own data without the setUp willReturn
  blocking overrides.

- tests/unit/Admin/BoardHumanModifiedFlagTest.php: add get_option() stub to
  setUp() covering prautoblogger_board_column_limit and
  prautoblogger_board_published_window_days. Required because M4 made
  get_in_review_cards() and get_published_cards() call get_option() for the
  column limit (previously hardcoded); Brain\Monkey disallows unmocked calls.

- tests/unit/Core/GenerationCheckpointRunnerTest.php: call wire_wpdb_for_lock()
  before on_generate_tick() in the empty-queue test so Generation_Lock::release()
  (called from Helpers::finalize()) has a $wpdb available.

Agent-Session: phase2-admin-m4-20260614

tests/unit/Admin/BoardHumanModifiedFlagTest.php

@@ -54,6 +54,15 @@ class BoardHumanModifiedFlagTest extends BaseTestCase {
 		);
 		Functions\when( 'get_edit_post_link' )->justReturn( 'https://example.com/edit' );
 		Functions\when( 'admin_url' )->alias( static fn( $p = '' ) => 'https://example.com/wp-admin/' . $p );
+		Functions\when( 'get_option' )->alias(
+			function ( string $name, $default = false ) {
+				$map = array(
+					'prautoblogger_board_column_limit'         => PRAUTOBLOGGER_DEFAULT_BOARD_COLUMN_LIMIT,
+					'prautoblogger_board_published_window_days' => 7,
+				);
+				return $map[ $name ] ?? $default;
+			}
+		);
 		\PRAutoBlogger_Run_Stage_State::flush_cache();
 	}