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/CommandInterface.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws;
+
+/**
+ * A command object encapsulates the input parameters used to control the
+ * creation of a HTTP request and processing of a HTTP response.
+ *
+ * Using the toArray() method will return the input parameters of the command
+ * as an associative array.
+ */
+interface CommandInterface extends \ArrayAccess, \Countable, \IteratorAggregate
+{
+    /**
+     * Converts the command parameters to an array
+     *
+     * @return array
+     */
+    public function toArray();
+    /**
+     * Get the name of the command
+     *
+     * @return string
+     */
+    public function getName();
+    /**
+     * Check if the command has a parameter by name.
+     *
+     * @param string $name Name of the parameter to check
+     *
+     * @return bool
+     */
+    public function hasParam($name);
+    /**
+     * Get the handler list used to transfer the command.
+     *
+     * @return HandlerList
+     */
+    public function getHandlerList();
+}