fix(2meet-data-optimizer): 1.4.2 acceptance fixes for archive sweep and uninstall

- Archive sweep waits until idx_original_meta exists (a plugin update does
  not run dbDelta; without the index NOT EXISTS scans the archive per row)
- Duplicate archive cleanup runs from WP-CLI only, never in a web activation
- Uninstall keeps the LatePoint add-on's tmdo_latepoint_db_version
- AJAX save errors stay on screen instead of fading after 2.5 s
- Verify: 2 new integration tests; unit 711, integration 612, phpcs 0, stan OK
- PR: PR-141 (2.4.2 correctness review)

includes/zones/class-tmdo-zone-archive.php

@@ -213,6 +213,10 @@ class TMDO_Zone_Archive {
 		// Rows already archived are skipped: the sweep used to copy the same
 		// trashed meta again every day (2.4.2 PR-136).
 		$table = self::table();
+		// Without the index each candidate scans the archive: wait for `wp tmdo install`.
+		if ( ! TMDO_IS_SQLITE && ! $wpdb->get_var( "SHOW INDEX FROM `{$table}` WHERE Key_name = 'idx_original_meta'" ) ) { // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- internal table name
+			return 0;
+		}
 
 		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from internal self::table()
 		$rows = $wpdb->get_results(