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/GuzzleHttp/Psr7/InflateStream.php

@@ -0,0 +1,33 @@
+<?php
+
+declare (strict_types=1);
+namespace DeliciousBrains\WP_Offload_Media\Aws3\GuzzleHttp\Psr7;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\StreamInterface;
+/**
+ * Uses PHP's zlib.inflate filter to inflate zlib (HTTP deflate, RFC1950) or gzipped (RFC1952) content.
+ *
+ * This stream decorator converts the provided stream to a PHP stream resource,
+ * then appends the zlib.inflate filter. The stream is then converted back
+ * to a Guzzle stream resource to be used as a Guzzle stream.
+ *
+ * @see https://datatracker.ietf.org/doc/html/rfc1950
+ * @see https://datatracker.ietf.org/doc/html/rfc1952
+ * @see https://www.php.net/manual/en/filters.compression.php
+ */
+final class InflateStream implements StreamInterface
+{
+    use StreamDecoratorTrait;
+    /** @var StreamInterface */
+    private $stream;
+    public function __construct(StreamInterface $stream)
+    {
+        $resource = StreamWrapper::getResource($stream);
+        // Specify window=15+32, so zlib will use header detection to both gzip (with header) and zlib data
+        // See https://www.zlib.net/manual.html#Advanced definition of inflateInit2
+        // "Add 32 to windowBits to enable zlib and gzip decoding with automatic header detection"
+        // Default window size is 15.
+        \stream_filter_append($resource, 'zlib.inflate', \STREAM_FILTER_READ, ['window' => 15 + 32]);
+        $this->stream = $stream->isSeekable() ? new Stream($resource) : new NoSeekStream(new Stream($resource));
+    }
+}