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/Notifications.svelte

@@ -0,0 +1,34 @@
+<script>
+	import {notifications} from "../js/stores";
+	import Notification from "./Notification.svelte";
+
+	export let component = Notification;
+	export let tab = "";
+	export let tabParent = "";
+
+	/**
+	 * Render the notification or not?
+	 */
+	function renderNotification( notification ) {
+		let not_dismissed = !notification.dismissed;
+		let valid_parent_tab = notification.only_show_on_tab === tab && notification.hide_on_parent !== true;
+		let valid_sub_tab = notification.only_show_on_tab === tabParent;
+		let show_on_all_tabs = !notification.only_show_on_tab;
+
+		return not_dismissed && (valid_parent_tab || valid_sub_tab || show_on_all_tabs);
+	}
+</script>
+
+{#if $notifications.length && Object.values( $notifications ).filter( notification => renderNotification( notification ) ).length}
+	<div id="notifications" class="notifications wrapper">
+		{#each $notifications as notification (notification.render_key)}
+			{#if renderNotification( notification )}
+				<svelte:component this={component} notification={notification}>
+					{#if notification.message}
+						<p>{@html notification.message}</p>
+					{/if}
+				</svelte:component>
+			{/if}
+		{/each}
+	</div>
+{/if}