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/Aws/EndpointV2/EndpointDefinitionProvider.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\EndpointV2;
+
+/**
+ * Provides Endpoint-related artifacts used for endpoint resolution
+ * and testing.
+ */
+class EndpointDefinitionProvider
+{
+    public static function getEndpointRuleset($service, $apiVersion, $baseDir = null)
+    {
+        return self::getData($service, $apiVersion, 'ruleset', $baseDir);
+    }
+    public static function getEndpointTests($service, $apiVersion, $baseDir = null)
+    {
+        return self::getData($service, $apiVersion, 'tests', $baseDir);
+    }
+    public static function getPartitions()
+    {
+        $basePath = __DIR__ . '/../data';
+        $file = '/partitions.json';
+        if (\file_exists($basePath . $file . '.php')) {
+            return require $basePath . $file . '.php';
+        } else {
+            return \json_decode(\file_get_contents($basePath . $file));
+        }
+    }
+    private static function getData($service, $apiVersion, $type, $baseDir)
+    {
+        $basePath = $baseDir ? $baseDir : __DIR__ . '/../data';
+        $serviceDir = $basePath . "/{$service}";
+        if (!\is_dir($serviceDir)) {
+            throw new \InvalidArgumentException('Invalid service name.');
+        }
+        if ($apiVersion === 'latest') {
+            $apiVersion = self::getLatest($service);
+        }
+        $rulesetPath = $serviceDir . '/' . $apiVersion;
+        if (!\is_dir($rulesetPath)) {
+            throw new \InvalidArgumentException('Invalid api version.');
+        }
+        $fileName = $type === 'tests' ? '/endpoint-tests-1' : '/endpoint-rule-set-1';
+        if (\file_exists($rulesetPath . $fileName . '.json.php')) {
+            return require $rulesetPath . $fileName . '.json.php';
+        } elseif (\file_exists($rulesetPath . $fileName . '.json')) {
+            return \json_decode(\file_get_contents($rulesetPath . $fileName . '.json'), \true);
+        } else {
+            throw new \InvalidArgumentException('Specified ' . $type . ' endpoint file for ' . $service . ' with api version ' . $apiVersion . ' does not exist.');
+        }
+    }
+    private static function getLatest($service)
+    {
+        $manifest = \DeliciousBrains\WP_Offload_Media\Aws3\Aws\manifest();
+        return $manifest[$service]['versions']['latest'];
+    }
+}