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/js/defaultPages.js

@@ -0,0 +1,144 @@
+import {get} from "svelte/store";
+import {location} from "svelte-spa-router";
+import {
+	strings,
+	storage_provider,
+	is_plugin_setup_with_credentials,
+	is_plugin_setup,
+	needs_access_keys,
+	delivery_provider
+} from "./stores";
+
+// Components used for default pages.
+import MediaPage from "../components/MediaPage.svelte";
+import StoragePage from "../components/StoragePage.svelte";
+import StorageProviderSubPage
+	from "../components/StorageProviderSubPage.svelte";
+import BucketSettingsSubPage from "../components/BucketSettingsSubPage.svelte";
+import SecuritySubPage from "../components/SecuritySubPage.svelte";
+import DeliveryPage from "../components/DeliveryPage.svelte";
+
+// Default pages, having a title means inclusion in main tabs.
+// NOTE: get() only resolves after initialization, hence arrow functions for getting titles.
+export const defaultPages = [
+	{
+		position: 0,
+		name: "media-library",
+		title: () => get( strings ).media_tab_title,
+		nav: true,
+		route: "/",
+		routeMatcher: /^\/(media\/.*)*$/,
+		component: MediaPage,
+		default: true
+	},
+	{
+		position: 200,
+		name: "storage",
+		route: "/storage/*",
+		component: StoragePage
+	},
+	{
+		position: 210,
+		name: "storage-provider",
+		title: () => get( strings ).storage_provider_tab_title,
+		subNav: true,
+		route: "/storage/provider",
+		component: StorageProviderSubPage,
+		default: true,
+		events: {
+			"page.initial.settings": ( data ) => {
+				// We need Storage Provider credentials for some pages to be useful.
+				if ( data.hasOwnProperty( "location" ) && get( needs_access_keys ) && !get( is_plugin_setup ) ) {
+					for ( const prefix of ["/storage", "/media", "/delivery"] ) {
+						if ( data.location.startsWith( prefix ) ) {
+							return true;
+						}
+					}
+
+					return data.location === "/";
+				}
+
+				return false;
+			}
+		}
+	},
+	{
+		position: 220,
+		name: "bucket",
+		title: () => get( strings ).bucket_tab_title,
+		subNav: true,
+		route: "/storage/bucket",
+		component: BucketSettingsSubPage,
+		enabled: () => {
+			return !get( needs_access_keys );
+		},
+		events: {
+			"page.initial.settings": ( data ) => {
+				// We need a bucket and region to have been verified before some pages are useful.
+				if ( data.hasOwnProperty( "location" ) && !get( needs_access_keys ) && !get( is_plugin_setup ) ) {
+					for ( const prefix of ["/storage", "/media", "/delivery"] ) {
+						if ( data.location.startsWith( prefix ) ) {
+							return true;
+						}
+					}
+
+					return data.location === "/";
+				}
+
+				return false;
+			},
+			"settings.save": ( data ) => {
+				// If currently in /storage/provider route, bucket is always next, assuming storage provider set up correctly.
+				return get( location ) === "/storage/provider" && !get( needs_access_keys );
+			}
+		}
+	},
+	{
+		position: 230,
+		name: "security",
+		title: () => get( strings ).security_tab_title,
+		subNav: true,
+		route: "/storage/security",
+		component: SecuritySubPage,
+		enabled: () => {
+			return get( is_plugin_setup_with_credentials ) && !get( storage_provider ).requires_acls;
+		},
+		events: {
+			"settings.save": ( data ) => {
+				// If currently in /storage/bucket route,
+				// and storage provider does not require ACLs,
+				// and bucket wasn't just created during initial set up
+				// with delivery provider compatible access control,
+				// then security is next.
+				if (
+					get( location ) === "/storage/bucket" &&
+					get( is_plugin_setup_with_credentials ) &&
+					!get( storage_provider ).requires_acls &&
+					(
+						!data.hasOwnProperty( "bucketSource" ) || // unexpected data issue
+						data.bucketSource !== "new" || // bucket not created
+						!data.hasOwnProperty( "initialSettings" ) || // unexpected data issue
+						!data.initialSettings.hasOwnProperty( "bucket" ) || // unexpected data issue
+						data.initialSettings.bucket.length > 0 || // bucket previously set
+						!data.hasOwnProperty( "settings" ) || // unexpected data issue
+						!data.settings.hasOwnProperty( "use-bucket-acls" ) || // unexpected data issue
+						(
+							!data.settings[ "use-bucket-acls" ] && // bucket not using ACLs ...
+							get( delivery_provider ).requires_acls // ... but delivery provider needs ACLs
+						)
+					)
+				) {
+					return true;
+				}
+
+				return false;
+			}
+		}
+	},
+	{
+		position: 300,
+		name: "delivery",
+		route: "/delivery/*",
+		component: DeliveryPage
+	},
+];