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/pro/background-processes/move-private-objects-process.php

@@ -0,0 +1,76 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Pro\Background_Processes;
+
+use AS3CF_Error;
+use DeliciousBrains\WP_Offload_Media\Items\Item;
+use Exception;
+
+class Move_Private_Objects_Process extends Move_Objects_Process {
+
+	/**
+	 * @var string
+	 */
+	protected $action = 'move_private_objects';
+
+	/**
+	 * Process items chunk.
+	 *
+	 * @param string $source_type
+	 * @param array  $source_ids
+	 * @param int    $blog_id
+	 *
+	 * @return array
+	 *
+	 * @throws Exception
+	 */
+	protected function process_items_chunk( $source_type, $source_ids, $blog_id ) {
+		/** @var Item $class */
+		$class         = $this->as3cf->get_source_type_class( $source_type );
+		$items_to_move = array();
+
+		if ( $this->as3cf->private_prefix_enabled() ) {
+			$new_private_prefix = $this->as3cf->get_setting( 'signed-urls-object-prefix' );
+		} else {
+			$new_private_prefix = '';
+		}
+
+		foreach ( $source_ids as $source_id ) {
+			$as3cf_item = $class::get_by_source_id( $source_id );
+
+			if ( $as3cf_item ) {
+				// Analyze current private prefix to see if it needs changing.
+				switch ( $this->should_move_to_new_private_prefix( $as3cf_item, $as3cf_item->private_prefix(), $new_private_prefix ) ) {
+					case self::MOVE_NO:
+					case self::MOVE_SAME:
+						break;
+					case self::MOVE_NOOP:
+						// If nothing is to be moved to new private prefix, just fix data.
+						$as3cf_item->set_private_prefix( $new_private_prefix );
+						$as3cf_item->save();
+						continue 2;
+					case self::MOVE_YES:
+						$items_to_move[ $source_id ] = array( 'prefix' => $as3cf_item->normalized_path_dir(), 'private_prefix' => $new_private_prefix );
+						break;
+				}
+			} else {
+				$name = $this->as3cf->get_source_type_name( $source_type );
+				AS3CF_Error::log( sprintf( 'Move Private Objects: Offload data for %s item with ID %d could not be found for analysis.', $name, $source_id ) );
+			}
+		}
+
+		$this->move_items( $items_to_move, $blog_id, $source_type );
+
+		// Whether moved or not, we processed every item.
+		return $source_ids;
+	}
+
+	/**
+	 * Get complete notice message.
+	 *
+	 * @return string
+	 */
+	protected function get_complete_message() {
+		return __( 'Finished moving media files to new private paths.', 'amazon-s3-and-cloudfront' );
+	}
+}