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/Aws3/Aws/Api/Serializer/Ec2ParamBuilder.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Serializer;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Shape;
+use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\ListShape;
+/**
+ * @internal
+ */
+class Ec2ParamBuilder extends QueryParamBuilder
+{
+    protected function queryName(Shape $shape, $default = null)
+    {
+        return ($shape['queryName'] ?: \ucfirst(@$shape['locationName'] ?: "")) ?: $default;
+    }
+    protected function isFlat(Shape $shape)
+    {
+        return \false;
+    }
+    protected function format_list(ListShape $shape, array $value, $prefix, &$query)
+    {
+        // Handle empty list serialization
+        if (!empty($value)) {
+            $items = $shape->getMember();
+            foreach ($value as $k => $v) {
+                $this->format($items, $v, $prefix . '.' . ($k + 1), $query);
+            }
+        }
+    }
+}