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

ui/pro/AssetsSettingsHeaderRow.svelte

@@ -0,0 +1,42 @@
+<script>
+	import {strings, urls} from "../js/stores";
+	import PanelRow from "../components/PanelRow.svelte";
+</script>
+
+
+<PanelRow header class="assets">
+	<img src="{$urls.assets + 'img/icon/assets.svg'}" alt="foo"/>
+	<div class="assets-details">
+		<h3>{$strings.assets_panel_header}</h3>
+		<p class="console-details">
+			{$strings.assets_panel_header_details}
+		</p>
+	</div>
+</PanelRow>
+
+<style>
+	:global(#as3cf-settings.wpome div.panel.settings .header) img {
+		width: var(--as3cf-settings-ctrl-width);
+		height: var(--as3cf-settings-ctrl-width);
+	}
+
+	.assets-details {
+		display: flex;
+		flex-direction: column;
+		flex: auto;
+		margin-left: var(--as3cf-settings-option-indent);
+		z-index: 1;
+	}
+
+	:global(#as3cf-settings.wpome div.panel) .assets-details h3 {
+		margin-left: 0;
+		margin-bottom: 0.5rem;
+	}
+
+	:global(#as3cf-settings.wpome div.panel) .console-details {
+		display: flex;
+		align-items: center;
+		color: var(--as3cf-color-gray-600);
+		font-size: 0.75rem;
+	}
+</style>