feat: add S3-compatible storage provider (MinIO, Ceph, R2, etc.)

Adds a new 'S3-Compatible Storage' provider that works with any
S3-API-compatible object storage service, including MinIO, Ceph,
Cloudflare R2, Backblaze B2, and others.

Changes:
- New provider class: classes/providers/storage/s3-compatible-provider.php
  - Provider key: s3compatible
  - Reads user-configured endpoint URL from settings
  - Uses path-style URL access (required by most S3-compatible services)
  - Supports credentials via AS3CF_S3COMPAT_ACCESS_KEY_ID /
    AS3CF_S3COMPAT_SECRET_ACCESS_KEY wp-config.php constants
  - Disables AWS-specific features (Block Public Access, Object Ownership)
- New provider SVG icons (s3compatible.svg, -link.svg, -round.svg)
- Registered provider in main plugin class with endpoint setting support
- Updated StorageProviderSubPage to show endpoint URL input for S3-compatible
- Built pro settings bundle with rollup (Svelte 4.2.19)
- Added package.json and updated rollup.config.mjs for pro-only builds

vendor/Gcp/symfony/polyfill-php81/bootstrap.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Gcp;
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+use DeliciousBrains\WP_Offload_Media\Gcp\Symfony\Polyfill\Php81 as p;
+if (\PHP_VERSION_ID >= 80100) {
+    return;
+}
+if (\defined('MYSQLI_REFRESH_SLAVE') && !\defined('MYSQLI_REFRESH_REPLICA')) {
+    \define('MYSQLI_REFRESH_REPLICA', 64);
+}
+if (!\function_exists('array_is_list')) {
+    function array_is_list(array $array) : bool
+    {
+        return p\Php81::array_is_list($array);
+    }
+}
+if (!\function_exists('enum_exists')) {
+    function enum_exists(string $enum, bool $autoload = \true) : bool
+    {
+        return $autoload && \class_exists($enum) && \false;
+    }
+}