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/MediaPage.svelte

@@ -0,0 +1,71 @@
+<script>
+	import {getContext, hasContext, onMount, setContext} from "svelte";
+	import {
+		is_plugin_setup,
+		settingsLocked,
+		strings,
+		settings_validation
+	} from "../js/stores";
+	import Page from "./Page.svelte";
+	import Notifications from "./Notifications.svelte";
+	import SubNav from "./SubNav.svelte";
+	import SubPages from "./SubPages.svelte";
+	import MediaSettings from "./MediaSettings.svelte";
+	import UrlPreview from "./UrlPreview.svelte";
+	import Footer from "./Footer.svelte";
+
+	export let name = "media";
+	export let params = {}; // Required for regex routes.
+	const _params = params; // Stops compiler warning for params;
+
+	let sidebar = null;
+	let render = false;
+
+	if ( hasContext( 'sidebar' ) ) {
+		sidebar = getContext( 'sidebar' );
+	}
+
+	// Let all child components know if settings are currently locked.
+	setContext( "settingsLocked", settingsLocked );
+
+	// We have a weird subnav here as both routes could be shown at same time.
+	// So they are grouped, and CSS decides which is shown when width stops both from being shown.
+	// The active route will determine the SubPage that is given the active class.
+	const routes = {
+		'*': MediaSettings,
+	}
+
+	$: items = [
+		{
+			route: "/",
+			title: () => $strings.storage_settings_title,
+			noticeIcon: $settings_validation[ "storage" ].type
+		},
+		{
+			route: "/media/delivery",
+			title: () => $strings.delivery_settings_title,
+			noticeIcon: $settings_validation[ "delivery" ].type
+		}
+	];
+
+	onMount( () => {
+		if ( $is_plugin_setup ) {
+			render = true;
+		}
+	} )
+</script>
+
+<Page {name} on:routeEvent>
+	{#if render}
+		<Notifications tab={name}/>
+		<SubNav {name} {items} subpage/>
+		<SubPages {name} {routes}/>
+		<UrlPreview/>
+	{/if}
+</Page>
+
+{#if sidebar && render}
+	<svelte:component this={sidebar}/>
+{/if}
+
+<Footer on:routeEvent/>