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/ClientInterface.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Exception\GuzzleException;
+use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Promise\PromiseInterface;
+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\UriInterface;
+/**
+ * Client interface for sending HTTP requests.
+ */
+interface ClientInterface
+{
+    /**
+     * The Guzzle major version.
+     */
+    public const MAJOR_VERSION = 7;
+    /**
+     * Send an HTTP request.
+     *
+     * @param RequestInterface $request Request to send
+     * @param array            $options Request options to apply to the given
+     *                                  request and to the transfer.
+     *
+     * @throws GuzzleException
+     */
+    public function send(RequestInterface $request, array $options = []) : ResponseInterface;
+    /**
+     * Asynchronously send an HTTP request.
+     *
+     * @param RequestInterface $request Request to send
+     * @param array            $options Request options to apply to the given
+     *                                  request and to the transfer.
+     */
+    public function sendAsync(RequestInterface $request, array $options = []) : PromiseInterface;
+    /**
+     * Create and send an HTTP request.
+     *
+     * Use an absolute path to override the base path of the client, or a
+     * relative path to append to the base path of the client. The URL can
+     * contain the query string as well.
+     *
+     * @param string              $method  HTTP method.
+     * @param string|UriInterface $uri     URI object or string.
+     * @param array               $options Request options to apply.
+     *
+     * @throws GuzzleException
+     */
+    public function request(string $method, $uri, array $options = []) : ResponseInterface;
+    /**
+     * Create and send an asynchronous HTTP request.
+     *
+     * Use an absolute path to override the base path of the client, or a
+     * relative path to append to the base path of the client. The URL can
+     * contain the query string as well. Use an array to provide a URL
+     * template and additional variables to use in the URL template expansion.
+     *
+     * @param string              $method  HTTP method
+     * @param string|UriInterface $uri     URI object or string.
+     * @param array               $options Request options to apply.
+     */
+    public function requestAsync(string $method, $uri, array $options = []) : PromiseInterface;
+    /**
+     * Get a client configuration option.
+     *
+     * These options include default request options of the client, a "handler"
+     * (if utilized by the concrete client), and a "base_uri" if utilized by
+     * the concrete client.
+     *
+     * @param string|null $option The config option to retrieve.
+     *
+     * @return mixed
+     *
+     * @deprecated ClientInterface::getConfig will be removed in guzzlehttp/guzzle:8.0.
+     */
+    public function getConfig(?string $option = null);
+}