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/LicencePage.svelte

@@ -0,0 +1,103 @@
+<script>
+	import {createEventDispatcher} from "svelte";
+	import {api, config, settings, strings} from "../js/stores";
+	import {autofocus} from "../js/autofocus";
+	import {licence} from "./stores";
+	import Page from "../components/Page.svelte";
+	import Notifications from "../components/Notifications.svelte";
+	import Button from "../components/Button.svelte";
+	import DefinedInWPConfig from "../components/DefinedInWPConfig.svelte";
+
+	const dispatch = createEventDispatcher();
+
+	export let name = "licence";
+
+	let value = "";
+
+	/**
+	 * Handles an "Activate License" button click.
+	 *
+	 * @param {Object} event
+	 *
+	 * @return {Promise<void>}
+	 */
+	async function handleActivateLicence( event ) {
+		const result = await api.post( "licences", { licence: value } );
+
+		await updateLicenceInfo( result )
+	}
+
+	/**
+	 * Handles a "Remove License" button click.
+	 *
+	 * @param {Object} event
+	 *
+	 * @return {Promise<void>}
+	 */
+	async function handleRemoveLicence( event ) {
+		value = "";
+		const result = await api.delete( "licences" );
+
+		await updateLicenceInfo( result )
+	}
+
+	/**
+	 * Update licence store with results of API call.
+	 *
+	 * @param {Object} response
+	 *
+	 * @return {Promise<void>}
+	 */
+	async function updateLicenceInfo( response ) {
+		if ( response.hasOwnProperty( "licences" ) ) {
+			config.update( currentConfig => {
+				return {
+					...currentConfig,
+					licences: response.licences
+				};
+			} );
+		}
+
+		// Regardless of what just happened, make sure our settings are in sync (includes reference to license).
+		await settings.fetch();
+	}
+</script>
+
+<Page {name} on:routeEvent>
+	<Notifications tab={name}/>
+	<h2 class="page-title">{$strings.licence_title}</h2>
+
+	<div class="licence-page wrapper" class:defined={$licence.is_set && $licence.is_defined}>
+		{#if $licence.is_set}
+			<label for="licence-key" class="screen-reader-text">{$strings.licence_title}</label>
+			<input
+				id="licence-key"
+				type="text"
+				class="licence-field disabled"
+				name="licence"
+				value={$licence.masked_licence}
+				disabled
+			>
+			{#if $licence.is_defined}
+				<DefinedInWPConfig defined/>
+			{:else}
+				<Button large outline on:click={handleRemoveLicence}>{$strings.remove_licence}</Button>
+			{/if}
+		{:else}
+			<label for="enter-licence-key" class="screen-reader-text">{$strings.enter_licence_key}</label>
+			<input
+				id="enter-licence-key"
+				type="text"
+				class="licence-field"
+				name="licence"
+				minlength="4"
+				placeholder={$strings.enter_licence_key}
+				bind:value
+				use:autofocus
+			>
+			<Button large primary on:click={handleActivateLicence} disabled={value.length === 0}>
+				{$strings.activate_licence}
+			</Button>
+		{/if}
+	</div>
+</Page>