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/Endpoint/PatternEndpointProvider.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Endpoint;
+
+/**
+ * Provides endpoints based on an endpoint pattern configuration array.
+ */
+class PatternEndpointProvider
+{
+    /** @var array */
+    private $patterns;
+    /**
+     * @param array $patterns Hash of endpoint patterns mapping to endpoint
+     *                        configurations.
+     */
+    public function __construct(array $patterns)
+    {
+        $this->patterns = $patterns;
+    }
+    public function __invoke(array $args = [])
+    {
+        $service = isset($args['service']) ? $args['service'] : '';
+        $region = isset($args['region']) ? $args['region'] : '';
+        $keys = ["{$region}/{$service}", "{$region}/*", "*/{$service}", "*/*"];
+        foreach ($keys as $key) {
+            if (isset($this->patterns[$key])) {
+                return $this->expand($this->patterns[$key], isset($args['scheme']) ? $args['scheme'] : 'https', $service, $region);
+            }
+        }
+        return null;
+    }
+    private function expand(array $config, $scheme, $service, $region)
+    {
+        $config['endpoint'] = $scheme . '://' . \strtr($config['endpoint'], ['{service}' => $service, '{region}' => $region]);
+        return $config;
+    }
+}