fix(purge): harden missing-option fallback against filtered defaults

Settings::get_defaults() runs every field through wp_stream_settings_option_fields,
which Network::get_network_admin_fields() uses to strip 'records_ttl' from the
per-site option's defaults set. Outside any admin context (Action Scheduler,
WP-CLI, system cron) the per-site option_key is in effect, so the filtered
defaults never contained general_records_ttl. Without this fallback the
auto-purge silently no-ops on every install where the option is missing,
defeating the whole point of fixing this on bloated sites.

Hardcoded fallback to 30 days (the documented default on the settings field
itself) when general_records_ttl is absent after the merge.

Caught by section 9 of the e2e plan.

Refs XWPENG-28

Author: PatelUtkarsh

classes/class-admin.php

@@ -927,7 +927,22 @@ public function purge_scheduled_action() {
 			$options = wp_parse_args( (array) get_option( 'wp_stream', array() ), $defaults );
 		}
 
-		if ( ! empty( $options['general_keep_records_indefinitely'] ) || empty( $options['general_records_ttl'] ) ) {
+		// Hardcoded TTL fallback. Settings::get_defaults() runs every settings
+		// field through the `wp_stream_settings_option_fields` filter, which
+		// Network::get_network_admin_fields() uses to strip the `records_ttl`
+		// field from the per-site option's defaults set. When this callback runs
+		// outside any admin context (Action Scheduler, WP-CLI, system cron), the
+		// per-site option_key is in effect, so the filtered defaults array does
+		// not contain general_records_ttl at all. Without this fallback the
+		// purge silently no-ops on every install where the option is missing,
+		// defeating the whole point of fixing this on bloated sites.
+		// Mirrors the 30-day default declared on the settings field itself
+		// (classes/class-settings.php, `records_ttl` field).
+		if ( empty( $options['general_records_ttl'] ) ) {
+			$options['general_records_ttl'] = 30;
+		}
+
+		if ( ! empty( $options['general_keep_records_indefinitely'] ) ) {
 			return;
 		}