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/StructureShape.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api;
+
+/**
+ * Represents a structure shape and resolve member shape references.
+ */
+class StructureShape extends Shape
+{
+    /**
+     * @var Shape[]
+     */
+    private $members;
+    public function __construct(array $definition, ShapeMap $shapeMap)
+    {
+        $definition['type'] = 'structure';
+        if (!isset($definition['members'])) {
+            $definition['members'] = [];
+        }
+        parent::__construct($definition, $shapeMap);
+    }
+    /**
+     * Gets a list of all members
+     *
+     * @return Shape[]
+     */
+    public function getMembers()
+    {
+        if (empty($this->members)) {
+            $this->generateMembersHash();
+        }
+        return $this->members;
+    }
+    /**
+     * Check if a specific member exists by name.
+     *
+     * @param string $name Name of the member to check
+     *
+     * @return bool
+     */
+    public function hasMember($name)
+    {
+        return isset($this->definition['members'][$name]);
+    }
+    /**
+     * Retrieve a member by name.
+     *
+     * @param string $name Name of the member to retrieve
+     *
+     * @return Shape
+     * @throws \InvalidArgumentException if the member is not found.
+     */
+    public function getMember($name)
+    {
+        $members = $this->getMembers();
+        if (!isset($members[$name])) {
+            throw new \InvalidArgumentException('Unknown member ' . $name);
+        }
+        return $members[$name];
+    }
+    private function generateMembersHash()
+    {
+        $this->members = [];
+        foreach ($this->definition['members'] as $name => $definition) {
+            $this->members[$name] = $this->shapeFor($definition);
+        }
+    }
+}