feat: initial release v1.1.0

Cloudflare R2 media offload manager for peptiderepo.com.
Built on WP Offload Media Lite. Supersedes the one-off migration script
and mu-plugin peptiderepo-r2-endpoint.php.

Features:
- Admin page under Peptide Repo > R2 Media Manager (shared umbrella menu)
- ensure_umbrella_menu() guard — safe for multi-plugin umbrella sharing
- Batch AJAX migration to R2 with pause/resume and progress bar
- Remove-local-copies batch with physical disk presence check
- Activity log table (wp_pr_r2_log) with self-healing on plugins_loaded
- Test R2 connection button
- R2 endpoint injection via as3cf_aws_s3_client_args filter

includes/class-r2-endpoint.php

@@ -0,0 +1,54 @@
+<?php
+/**
+ * What:    Injects the Cloudflare R2 endpoint into WP Offload Media's AWS SDK client.
+ *          Supersedes wp-content/mu-plugins/peptiderepo-r2-endpoint.php — that
+ *          mu-plugin should be deleted once this plugin is active.
+ * Who:     Registered via `as3cf_aws_s3_client_args` filter; fires whenever WP
+ *          Offload Media initialises its S3 client (uploads, deletes, URL signing).
+ * Depends: WP Offload Media Lite (amazon-s3-and-cloudfront).
+ *
+ * @see  peptiderepo-r2-manager.php   (bootstraps this class)
+ * @see  https://deliciousbrains.com/wp-offload-media/doc/custom-s3-compatible-storage/
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+class PR_R2_Endpoint {
+
+	/**
+	 * Cloudflare R2 account-level S3-compatible endpoint.
+	 * Using the account endpoint (not the public URL) so the AWS SDK can reach
+	 * the bucket via path-style access regardless of custom domain routing.
+	 */
+	const ENDPOINT = 'https://a16f4baa82a1074c47f696e7cb6d5995.r2.cloudflarestorage.com';
+
+	/**
+	 * Register the endpoint-injection filter.
+	 * Called once from the plugin bootstrap.
+	 *
+	 * @return void
+	 */
+	public static function init(): void {
+		add_filter( 'as3cf_aws_s3_client_args', [ __CLASS__, 'inject_r2_endpoint' ], 10, 1 );
+	}
+
+	/**
+	 * Override the AWS SDK S3 client endpoint to Cloudflare R2.
+	 *
+	 * Uses path-style endpoint so the bucket name appears in the URL path
+	 * (required with the account-level R2 endpoint, which doesn't support
+	 * virtual-hosted-style bucket subdomains).
+	 *
+	 * @param  array<string,mixed> $args  AWS SDK client constructor args from WP Offload Media.
+	 * @return array<string,mixed>        Modified args with R2 endpoint injected.
+	 *
+	 * Side effects: none — pure filter.
+	 */
+	public static function inject_r2_endpoint( array $args ): array {
+		$args['endpoint']                = self::ENDPOINT;
+		$args['use_path_style_endpoint'] = true;
+		return $args;
+	}
+}