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

classes/as3cf-error.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * Error
+ *
+ * @package     amazon-s3-and-cloudfront
+ * @subpackage  Classes/Error
+ * @copyright   Copyright (c) 2015, Delicious Brains
+ * @license     http://opensource.org/licenses/gpl-2.0.php GNU Public License
+ * @since       0.9.12
+ */
+
+// Exit if accessed directly
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * AS3CF_Error Class
+ *
+ * This class handles error logging
+ *
+ * @since 0.9.12
+ */
+class AS3CF_Error {
+
+	/**
+	 * Wrapper for error logging a message with plugin prefix
+	 *
+	 * phpcs:disable WordPress.PHP.DevelopmentFunctions
+	 *
+	 * @param mixed  $message
+	 * @param string $plugin_prefix
+	 */
+	public static function log( $message, $plugin_prefix = '' ) {
+		$prefix = 'AS3CF';
+		if ( '' !== $plugin_prefix ) {
+			$prefix .= '_' . $plugin_prefix;
+		}
+
+		$prefix .= ': ';
+
+		if ( is_array( $message ) || is_object( $message ) ) {
+			error_log( $prefix . print_r( $message, true ) );
+		} else {
+			error_log( $prefix . $message );
+		}
+	}
+}