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/Parser/PayloadParserTrait.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Parser;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Parser\Exception\ParserException;
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\ResponseInterface;
+trait PayloadParserTrait
+{
+    /**
+     * @param string $json
+     *
+     * @throws ParserException
+     *
+     * @return array
+     */
+    private function parseJson($json, $response)
+    {
+        $jsonPayload = \json_decode($json, \true);
+        if (\JSON_ERROR_NONE !== \json_last_error()) {
+            throw new ParserException('Error parsing JSON: ' . \json_last_error_msg(), 0, null, ['response' => $response]);
+        }
+        return $jsonPayload;
+    }
+    /**
+     * @param string $xml
+     *
+     * @throws ParserException
+     *
+     * @return \SimpleXMLElement
+     */
+    protected function parseXml($xml, $response)
+    {
+        $priorSetting = \libxml_use_internal_errors(\true);
+        try {
+            \libxml_clear_errors();
+            $xmlPayload = new \SimpleXMLElement($xml);
+            if ($error = \libxml_get_last_error()) {
+                throw new \RuntimeException($error->message);
+            }
+        } catch (\Exception $e) {
+            throw new ParserException("Error parsing XML: {$e->getMessage()}", 0, $e, ['response' => $response]);
+        } finally {
+            \libxml_use_internal_errors($priorSetting);
+        }
+        return $xmlPayload;
+    }
+}