fix(fusion_whitelabels): keep brand_promotion t-call so other modules can xpath onto it

The footer-credit override used position="replace" against the parent div
of <t t-call="web.brand_promotion"/>, which deleted the element from the
merged web.frontend_layout view. Any later module that anchors on that
t-call (e.g. Enterprise planning's planning.frontend_layout) failed to
install with "Element <xpath expr=//t[@t-call='web.brand_promotion']>
cannot be located in parent view".

Switched to position="after" on the t-call element itself. Odoo's branding
remains hidden via the existing fusion_whitelabels_nexa_brand_promotion
inherit (d-none on .o_brand_promotion), and the Nexa credit still renders.

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

fusion_whitelabels/__manifest__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 {
     "name": "Fusion Whitelabels",
-    "version": "19.0.1.4.3",
+    "version": "19.0.1.4.4",
     "category": "Website",
     "summary": "Replace Odoo frontend promotional branding with Nexa Systems whitelabeling.",
     "description": """