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/Cookie/FileCookieJar.php

@@ -0,0 +1,92 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Cookie;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Utils;
+/**
+ * Persists non-session cookies using a JSON formatted file
+ */
+class FileCookieJar extends CookieJar
+{
+    /**
+     * @var string filename
+     */
+    private $filename;
+    /**
+     * @var bool Control whether to persist session cookies or not.
+     */
+    private $storeSessionCookies;
+    /**
+     * Create a new FileCookieJar object
+     *
+     * @param string $cookieFile          File to store the cookie data
+     * @param bool   $storeSessionCookies Set to true to store session cookies
+     *                                    in the cookie jar.
+     *
+     * @throws \RuntimeException if the file cannot be found or created
+     */
+    public function __construct(string $cookieFile, bool $storeSessionCookies = \false)
+    {
+        parent::__construct();
+        $this->filename = $cookieFile;
+        $this->storeSessionCookies = $storeSessionCookies;
+        if (\file_exists($cookieFile)) {
+            $this->load($cookieFile);
+        }
+    }
+    /**
+     * Saves the file when shutting down
+     */
+    public function __destruct()
+    {
+        $this->save($this->filename);
+    }
+    /**
+     * Saves the cookies to a file.
+     *
+     * @param string $filename File to save
+     *
+     * @throws \RuntimeException if the file cannot be found or created
+     */
+    public function save(string $filename) : void
+    {
+        $json = [];
+        /** @var SetCookie $cookie */
+        foreach ($this as $cookie) {
+            if (CookieJar::shouldPersist($cookie, $this->storeSessionCookies)) {
+                $json[] = $cookie->toArray();
+            }
+        }
+        $jsonStr = Utils::jsonEncode($json);
+        if (\false === \file_put_contents($filename, $jsonStr, \LOCK_EX)) {
+            throw new \RuntimeException("Unable to save file {$filename}");
+        }
+    }
+    /**
+     * Load cookies from a JSON formatted file.
+     *
+     * Old cookies are kept unless overwritten by newly loaded ones.
+     *
+     * @param string $filename Cookie file to load.
+     *
+     * @throws \RuntimeException if the file cannot be loaded.
+     */
+    public function load(string $filename) : void
+    {
+        $json = \file_get_contents($filename);
+        if (\false === $json) {
+            throw new \RuntimeException("Unable to load file {$filename}");
+        }
+        if ($json === '') {
+            return;
+        }
+        $data = Utils::jsonDecode($json, \true);
+        if (\is_array($data)) {
+            foreach ($data as $cookie) {
+                $this->setCookie(new SetCookie($cookie));
+            }
+        } elseif (\is_scalar($data) && !empty($data)) {
+            throw new \RuntimeException("Invalid cookie file: {$filename}");
+        }
+    }
+}