fix(2meet-data-optimizer): archive sweep copies each trashed meta row once

- sweep() skips meta rows already in wpdo_archive (NOT EXISTS on
  original_meta_id): it copied the same trashed meta again every day and
  wpdo_archive has no unique key (dev20: 300 rows for 150 meta rows)
- TMDO_Zone_Archive::remove_duplicates() keeps the first copy per
  original_meta_id (rows without one are left alone); install() runs it,
  so `wp tmdo install` cleans existing sites
- wpdo_archive gets KEY idx_original_meta for the lookup (new installs;
  existing sites via `wp tmdo install`). SCHEMA_VERSION is not bumped, so
  no web request runs dbDelta
- Verify: ZoneArchiveIntegrationTest (2 new); dev20 read-only check: 150 of
  300 rows would be removed; unit 709, integration 608, phpcs 0, stan OK
- PR: PR-136 (manual F-6)

includes/class-tmdo-installer.php

@@ -217,6 +217,15 @@ class TMDO_Installer {
 		// Idempotent — only creates tables that don't already exist.
 		self::install_v2_tables();
 
+		// 1.4.2: archive sweeps before this release copied trashed meta daily.
+		if ( class_exists( 'TMDO_Zone_Archive' ) ) {
+			global $wpdb;
+			$archive = TMDO_Zone_Archive::table();
+			if ( $archive === $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $wpdb->esc_like( $archive ) ) ) ) {
+				TMDO_Zone_Archive::remove_duplicates();
+			}
+		}
+
 		update_option( 'wpdo_db_version', self::SCHEMA_VERSION );
 
 		// Register wpdo_features with autoload=no so it doesn't inflate every page load.
@@ -1440,7 +1449,8 @@ class TMDO_Installer {
   original_meta_id bigint(20) unsigned NOT NULL DEFAULT 0,
   PRIMARY KEY (id),
   KEY idx_post_id (post_id),
-  KEY idx_post_type_date (post_type, archived_at)
+  KEY idx_post_type_date (post_type, archived_at),
+  KEY idx_original_meta (original_meta_id)
 ) {$charset};";
 
 		foreach ( $sqls as $sql ) {