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/GuzzleHttp/Handler/EasyHandle.php

@@ -0,0 +1,91 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Handler;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Psr7\Response;
+use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Utils;
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\RequestInterface;
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\ResponseInterface;
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\StreamInterface;
+/**
+ * Represents a cURL easy handle and the data it populates.
+ *
+ * @internal
+ */
+final class EasyHandle
+{
+    /**
+     * @var resource|\CurlHandle cURL resource
+     */
+    public $handle;
+    /**
+     * @var StreamInterface Where data is being written
+     */
+    public $sink;
+    /**
+     * @var array Received HTTP headers so far
+     */
+    public $headers = [];
+    /**
+     * @var ResponseInterface|null Received response (if any)
+     */
+    public $response;
+    /**
+     * @var RequestInterface Request being sent
+     */
+    public $request;
+    /**
+     * @var array Request options
+     */
+    public $options = [];
+    /**
+     * @var int cURL error number (if any)
+     */
+    public $errno = 0;
+    /**
+     * @var \Throwable|null Exception during on_headers (if any)
+     */
+    public $onHeadersException;
+    /**
+     * @var \Exception|null Exception during createResponse (if any)
+     */
+    public $createResponseException;
+    /**
+     * Attach a response to the easy handle based on the received headers.
+     *
+     * @throws \RuntimeException if no headers have been received or the first
+     *                           header line is invalid.
+     */
+    public function createResponse() : void
+    {
+        [$ver, $status, $reason, $headers] = HeaderProcessor::parseHeaders($this->headers);
+        $normalizedKeys = Utils::normalizeHeaderKeys($headers);
+        if (!empty($this->options['decode_content']) && isset($normalizedKeys['content-encoding'])) {
+            $headers['x-encoded-content-encoding'] = $headers[$normalizedKeys['content-encoding']];
+            unset($headers[$normalizedKeys['content-encoding']]);
+            if (isset($normalizedKeys['content-length'])) {
+                $headers['x-encoded-content-length'] = $headers[$normalizedKeys['content-length']];
+                $bodyLength = (int) $this->sink->getSize();
+                if ($bodyLength) {
+                    $headers[$normalizedKeys['content-length']] = $bodyLength;
+                } else {
+                    unset($headers[$normalizedKeys['content-length']]);
+                }
+            }
+        }
+        // Attach a response to the easy handle with the parsed headers.
+        $this->response = new Response($status, $headers, $this->sink, $ver, $reason);
+    }
+    /**
+     * @param string $name
+     *
+     * @return void
+     *
+     * @throws \BadMethodCallException
+     */
+    public function __get($name)
+    {
+        $msg = $name === 'handle' ? 'The EasyHandle has been released' : 'Invalid property: ' . $name;
+        throw new \BadMethodCallException($msg);
+    }
+}