Initial import of fitme3070.pt platform

Plain-PHP fleet platform with id.andmore.pt SSO. Wires shared/platform-tools
as a submodule (platform_update, backups, git/migration tools) like the other
platforms.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

config/functions_backup.php

@@ -0,0 +1,2 @@
+<?php
+require_once __DIR__ . '/../shared/platform-tools/functions_backup.php';