Add TCF v2.2 bridge mode for external CMP integration (v1.3.0)

New cmp_mode setting toggles between the built-in banner (default,
unchanged) and a bridge mode that defers banner UX to an external
IAB TCF v2.2 certified CMP — e.g. Google's free Privacy & messaging
(Funding Choices) or Tarteaucitron.js — and listens to __tcfapi to
keep custom-script gating, attribution preservation, the att_cc_consent
cookie cache and the WP Consent API bridge in sync. Lets sites that
need a Google-certified CMP for EEA/UK AdSense/AdMob serving keep
using this plugin for everything except the consent UI itself.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

includes/class-att-consent.php

@@ -29,6 +29,7 @@ class ATT_Consent {
 		'ga4_measurement_id' => '',
 		'gtm_container_id'   => '',
 		'consent_mode'       => 'advanced',
+		'cmp_mode'           => 'self',
 		'banner_position'        => 'bottom',
 		'consent_expiry'         => 365,
 		'floating_widget'        => 'bottom-right',