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/Gcp/google/common-protos/src/Api/Billing/BillingDestination.php

@@ -0,0 +1,109 @@
+<?php
+
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/api/billing.proto
+namespace DeliciousBrains\WP_Offload_Media\Gcp\Google\Api\Billing;
+
+use DeliciousBrains\WP_Offload_Media\Gcp\Google\Protobuf\Internal\GPBType;
+use DeliciousBrains\WP_Offload_Media\Gcp\Google\Protobuf\Internal\RepeatedField;
+use DeliciousBrains\WP_Offload_Media\Gcp\Google\Protobuf\Internal\GPBUtil;
+/**
+ * Configuration of a specific billing destination (Currently only support
+ * bill against consumer project).
+ *
+ * Generated from protobuf message <code>google.api.Billing.BillingDestination</code>
+ */
+class BillingDestination extends \DeliciousBrains\WP_Offload_Media\Gcp\Google\Protobuf\Internal\Message
+{
+    /**
+     * The monitored resource type. The type must be defined in
+     * [Service.monitored_resources][google.api.Service.monitored_resources]
+     * section.
+     *
+     * Generated from protobuf field <code>string monitored_resource = 1;</code>
+     */
+    protected $monitored_resource = '';
+    /**
+     * Names of the metrics to report to this billing destination.
+     * Each name must be defined in
+     * [Service.metrics][google.api.Service.metrics] section.
+     *
+     * Generated from protobuf field <code>repeated string metrics = 2;</code>
+     */
+    private $metrics;
+    /**
+     * Constructor.
+     *
+     * @param array $data {
+     *     Optional. Data for populating the Message object.
+     *
+     *     @type string $monitored_resource
+     *           The monitored resource type. The type must be defined in
+     *           [Service.monitored_resources][google.api.Service.monitored_resources]
+     *           section.
+     *     @type array<string>|\Google\Protobuf\Internal\RepeatedField $metrics
+     *           Names of the metrics to report to this billing destination.
+     *           Each name must be defined in
+     *           [Service.metrics][google.api.Service.metrics] section.
+     * }
+     */
+    public function __construct($data = NULL)
+    {
+        \DeliciousBrains\WP_Offload_Media\Gcp\GPBMetadata\Google\Api\Billing::initOnce();
+        parent::__construct($data);
+    }
+    /**
+     * The monitored resource type. The type must be defined in
+     * [Service.monitored_resources][google.api.Service.monitored_resources]
+     * section.
+     *
+     * Generated from protobuf field <code>string monitored_resource = 1;</code>
+     * @return string
+     */
+    public function getMonitoredResource()
+    {
+        return $this->monitored_resource;
+    }
+    /**
+     * The monitored resource type. The type must be defined in
+     * [Service.monitored_resources][google.api.Service.monitored_resources]
+     * section.
+     *
+     * Generated from protobuf field <code>string monitored_resource = 1;</code>
+     * @param string $var
+     * @return $this
+     */
+    public function setMonitoredResource($var)
+    {
+        GPBUtil::checkString($var, True);
+        $this->monitored_resource = $var;
+        return $this;
+    }
+    /**
+     * Names of the metrics to report to this billing destination.
+     * Each name must be defined in
+     * [Service.metrics][google.api.Service.metrics] section.
+     *
+     * Generated from protobuf field <code>repeated string metrics = 2;</code>
+     * @return \Google\Protobuf\Internal\RepeatedField
+     */
+    public function getMetrics()
+    {
+        return $this->metrics;
+    }
+    /**
+     * Names of the metrics to report to this billing destination.
+     * Each name must be defined in
+     * [Service.metrics][google.api.Service.metrics] section.
+     *
+     * Generated from protobuf field <code>repeated string metrics = 2;</code>
+     * @param array<string>|\Google\Protobuf\Internal\RepeatedField $var
+     * @return $this
+     */
+    public function setMetrics($var)
+    {
+        $arr = GPBUtil::checkRepeatedField($var, \DeliciousBrains\WP_Offload_Media\Gcp\Google\Protobuf\Internal\GPBType::STRING);
+        $this->metrics = $arr;
+        return $this;
+    }
+}