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/Api/Parser/MetadataParserTrait.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Parser;
+
+use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\DateTimeResult;
+use DeliciousBrains\WP_Offload_Media\Aws3\Aws\Api\Shape;
+use DeliciousBrains\WP_Offload_Media\Aws3\Psr\Http\Message\ResponseInterface;
+trait MetadataParserTrait
+{
+    /**
+     * Extract a single header from the response into the result.
+     */
+    protected function extractHeader($name, Shape $shape, ResponseInterface $response, &$result)
+    {
+        $value = $response->getHeaderLine($shape['locationName'] ?: $name);
+        switch ($shape->getType()) {
+            case 'float':
+            case 'double':
+                $value = (float) $value;
+                break;
+            case 'long':
+                $value = (int) $value;
+                break;
+            case 'boolean':
+                $value = \filter_var($value, \FILTER_VALIDATE_BOOLEAN);
+                break;
+            case 'blob':
+                $value = \base64_decode($value);
+                break;
+            case 'timestamp':
+                try {
+                    $value = DateTimeResult::fromTimestamp($value, !empty($shape['timestampFormat']) ? $shape['timestampFormat'] : null);
+                    break;
+                } catch (\Exception $e) {
+                    // If the value cannot be parsed, then do not add it to the
+                    // output structure.
+                    return;
+                }
+            case 'string':
+                if ($shape['jsonvalue']) {
+                    $value = $this->parseJson(\base64_decode($value), $response);
+                }
+                break;
+        }
+        $result[$name] = $value;
+    }
+    /**
+     * Extract a map of headers with an optional prefix from the response.
+     */
+    protected function extractHeaders($name, Shape $shape, ResponseInterface $response, &$result)
+    {
+        // Check if the headers are prefixed by a location name
+        $result[$name] = [];
+        $prefix = $shape['locationName'];
+        $prefixLen = \strlen($prefix);
+        foreach ($response->getHeaders() as $k => $values) {
+            if (!$prefixLen) {
+                $result[$name][$k] = \implode(', ', $values);
+            } elseif (\stripos($k, $prefix) === 0) {
+                $result[$name][\substr($k, $prefixLen)] = \implode(', ', $values);
+            }
+        }
+    }
+    /**
+     * Places the status code of the response into the result array.
+     */
+    protected function extractStatus($name, ResponseInterface $response, array &$result)
+    {
+        $result[$name] = (int) $response->getStatusCode();
+    }
+}