feat(materials): add campaign materials overlay for sessions

Let GMs manage and show images over the scene from the editor and control panel, with zoom tools, help docs, and full ru/en i18n.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/renderer/materials/main.tsx

@@ -0,0 +1,20 @@
+import React from 'react';
+import { createRoot } from 'react-dom/client';
+
+import '../shared/ui/globals.css';
+import { EditorI18nProvider } from '../editor/i18n/EditorI18nContext';
+
+import { MaterialsApp } from './MaterialsApp';
+
+const rootEl = document.getElementById('root');
+if (!rootEl) {
+  throw new Error('Missing #root element');
+}
+
+createRoot(rootEl).render(
+  <React.StrictMode>
+    <EditorI18nProvider>
+      <MaterialsApp />
+    </EditorI18nProvider>
+  </React.StrictMode>,
+);