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/components/SettingsValidationStatusRow.svelte

@@ -0,0 +1,38 @@
+<script>
+	import {
+		settings_validation,
+		urls
+	} from "../js/stores";
+	import CheckAgain from "./CheckAgain.svelte";
+
+	export let section = "";
+
+	$: success = $settings_validation[ section ].type === "success";
+	$: warning = $settings_validation[ section ].type === "warning";
+	$: error = $settings_validation[ section ].type === "error";
+	$: info = $settings_validation[ section ].type === "info";
+	$: type = $settings_validation[ section ].type;
+
+	$: message = '<p>' + $settings_validation[ section ].message + '</p>';
+	$: iconURL = $urls.assets + "img/icon/notification-" + $settings_validation[ section ].type + ".svg";
+</script>
+
+<div
+	class="notification in-panel multiline {section}"
+	class:success
+	class:warning
+	class:error
+	class:info
+>
+	<div class="content in-panel">
+		<div class="icon type in-panel">
+			<img class="icon type" src={iconURL} alt="{type} icon"/>
+		</div>
+
+		<div class="body">
+			{@html message}
+		</div>
+
+		<CheckAgain section={section}/>
+	</div>
+</div>