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/providers/storage/streams/gcp-gcs-stream-wrapper.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Providers\Storage\Streams;
+
+use DeliciousBrains\WP_Offload_Media\Gcp\Google\Cloud\Storage\StorageClient;
+use DeliciousBrains\WP_Offload_Media\Gcp\Google\Cloud\Storage\StreamWrapper;
+
+class GCP_GCS_Stream_Wrapper extends StreamWrapper {
+
+	public static $wrapper;
+
+	/**
+	 * Register the 'gs://' stream wrapper
+	 *
+	 * @param StorageClient $client   Client to use with the stream wrapper
+	 * @param string        $protocol Protocol to register as.
+	 */
+	public static function register( StorageClient $client, $protocol = 'gs' ) {
+		// Keep a shadow copy of the protocol for use with context options.
+		static::$wrapper = $protocol;
+
+		parent::register( $client, $protocol );
+	}
+
+	/**
+	 * Overrides so we don't check for stat on directories
+	 *
+	 * @param string $path
+	 * @param int    $flags
+	 *
+	 * @return array
+	 */
+	public function url_stat( $path, $flags ) {
+		$extension = pathinfo( $path, PATHINFO_EXTENSION );
+		// If the path is a directory then return it as always existing.
+		if ( ! $extension ) {
+			return array(
+				0         => 0,
+				'dev'     => 0,
+				1         => 0,
+				'ino'     => 0,
+				2         => 16895,
+				'mode'    => 16895,
+				3         => 0,
+				'nlink'   => 0,
+				4         => 0,
+				'uid'     => 0,
+				5         => 0,
+				'gid'     => 0,
+				6         => -1,
+				'rdev'    => -1,
+				7         => 0,
+				'size'    => 0,
+				8         => 0,
+				'atime'   => 0,
+				9         => 0,
+				'mtime'   => 0,
+				10        => 0,
+				'ctime'   => 0,
+				11        => -1,
+				'blksize' => -1,
+				12        => -1,
+				'blocks'  => -1,
+			);
+		}
+
+		return parent::url_stat( $path, $flags );
+	}
+}