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/NoTools.svelte

@@ -0,0 +1,33 @@
+<script>
+	import {strings, urls} from "../js/stores";
+	import Upsell from "../components/Upsell.svelte";
+
+	let benefits = [
+		{
+			icon: $urls.assets + "img/icon/offload-remaining.svg",
+			alt: "offload icon",
+			text: $strings.tools_uppsell_benefits.offload,
+		},
+		{
+			icon: $urls.assets + "img/icon/download.svg",
+			alt: "download icon",
+			text: $strings.tools_uppsell_benefits.download,
+		},
+		{
+			icon: $urls.assets + "img/icon/remove-from-bucket.svg",
+			alt: "remove from bucket icon",
+			text: $strings.tools_uppsell_benefits.remove_bucket,
+		},
+		{
+			icon: $urls.assets + "img/icon/remove-from-server.svg",
+			alt: "remove from server icon",
+			text: $strings.tools_uppsell_benefits.remove_server,
+		},
+	];
+</script>
+
+<Upsell {benefits}>
+	<div slot="heading">{$strings.no_tools_header}</div>
+
+	<div slot="description">{@html $strings.no_tools_description}</div>
+</Upsell>