refactor: 全部 128 個生產檔加入 declare(strict_types=1)（PR-H）

對齊 A v3.2.0。型別強制會把隱式轉換變成 TypeError，所以一次全檔加入
並跑完整測試（unit 451 / integration 398 全綠，無迴歸）。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TbG1keQQ7XBa7qMQY16KCY

includes/migration/class-tmdo-migration-phase-base.php

@@ -6,6 +6,8 @@
  * @since 3.0.1
  */
 
+declare(strict_types=1);
+
 // phpcs:disable Squiz.Commenting.FunctionComment,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.PHP.YodaConditions,WordPress.Security.EscapeOutput.OutputNotEscaped -- Internal helpers; SQL composed from registry-validated identifiers; exception messages not echoed.
 
 if ( ! defined( 'ABSPATH' ) ) {