chore(2meet-data-optimizer): make the hardening branch pass PHPStan and PHPCS

- CI PHPStan (level 6, baseline for pre-existing debt) failed on 35 errors in
  code added on hardening/2.0: missing iterable value types (PHPDoc only), a
  redundant method_exists() in uninstall.php, and the new WP-CLI commands
  registered as array('Class', 'instanceMethod') — now array(new Class(), ...)
- Local runs had been masked by a PHPStan tmpDir shared with the act CI runner
  (cached container pointing at a removed phar); use a private tmpDir
- Verify: phpstan (private tmpDir) no errors, phpcs clean on changed files,
  phpunit Unit 658 OK; dev22 (running this branch) CLI post-status-sync /
  bridge-restore-native dry runs OK

includes/migration/class-tmdo-post-group-reconciler.php

@@ -72,7 +72,7 @@ final class TMDO_Post_Group_Reconciler {
 	 *
 	 * @param bool $dry_run Count only; write nothing.
 	 * @param int  $batch   Rows per batch.
-	 * @return array{moves: array<int, array>, enabled: bool}
+	 * @return array{moves: array<int, array<string, mixed>>, enabled: bool}
 	 */
 	public static function run( bool $dry_run = false, int $batch = 500 ): array {
 		global $wpdb;
@@ -165,9 +165,9 @@ final class TMDO_Post_Group_Reconciler {
 	/**
 	 * FROM/WHERE for non-NULL legacy values of the move's post types.
 	 *
-	 * @param array  $move   One entry of plan().
-	 * @param string $id_col Entity id column of the flat tables.
-	 * @return array{0:string, 1:array}
+	 * @param array<string, mixed> $move   One entry of plan().
+	 * @param string               $id_col Entity id column of the flat tables.
+	 * @return array{0:string, 1:array<int, mixed>}
 	 */
 	private static function source_clause( array $move, string $id_col ): array {
 		global $wpdb;
@@ -184,9 +184,9 @@ final class TMDO_Post_Group_Reconciler {
 	/**
 	 * Upsert one column of the target group rows and drop their cached copies.
 	 *
-	 * @param array  $move   One entry of plan().
-	 * @param string $id_col Entity id column of the flat tables.
-	 * @param array  $rows   Source rows: list of { id, v }.
+	 * @param array<string, mixed>             $move   One entry of plan().
+	 * @param string                           $id_col Entity id column of the flat tables.
+	 * @param array<int, array<string, mixed>> $rows   Source rows: list of { id, v }.
 	 * @return int Rows written.
 	 */
 	private static function copy_rows( array $move, string $id_col, array $rows ): int {