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/AbstractModel.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api;
+
+/**
+ * Base class that is used by most API shapes
+ */
+abstract class AbstractModel implements \ArrayAccess
+{
+    /** @var array */
+    protected $definition;
+    /** @var ShapeMap */
+    protected $shapeMap;
+    /** @var array */
+    protected $contextParam;
+    /**
+     * @param array    $definition Service description
+     * @param ShapeMap $shapeMap   Shapemap used for creating shapes
+     */
+    public function __construct(array $definition, ShapeMap $shapeMap)
+    {
+        $this->definition = $definition;
+        $this->shapeMap = $shapeMap;
+        if (isset($definition['contextParam'])) {
+            $this->contextParam = $definition['contextParam'];
+        }
+    }
+    public function toArray()
+    {
+        return $this->definition;
+    }
+    /**
+     * @return mixed|null
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetGet($offset)
+    {
+        return isset($this->definition[$offset]) ? $this->definition[$offset] : null;
+    }
+    /**
+     * @return void
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetSet($offset, $value)
+    {
+        $this->definition[$offset] = $value;
+    }
+    /**
+     * @return bool
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetExists($offset)
+    {
+        return isset($this->definition[$offset]);
+    }
+    /**
+     * @return void
+     */
+    #[\ReturnTypeWillChange]
+    public function offsetUnset($offset)
+    {
+        unset($this->definition[$offset]);
+    }
+    protected function shapeAt($key)
+    {
+        if (!isset($this->definition[$key])) {
+            throw new \InvalidArgumentException('Expected shape definition at ' . $key);
+        }
+        return $this->shapeFor($this->definition[$key]);
+    }
+    protected function shapeFor(array $definition)
+    {
+        return isset($definition['shape']) ? $this->shapeMap->resolve($definition) : Shape::create($definition, $this->shapeMap);
+    }
+}