React 19 modernization: forwardRef removal, Compiler, ErrorBoundary, Suspense, native <script>

Adopt React 19 idioms across the codebase. The runtime was already on
react@19.2.5 but no React 19 APIs were in use.

- forwardRef -> ref-as-prop in 7 layout/component files
  (NitroInput/Button/ItemCountBadge/Card×5/InfiniteGridItem,
  ToolbarItemView, AvatarEditorIcon)
- <Ctx.Provider> -> <Ctx> in 6 contexts (CatalogAdmin, FloorplanEditor,
  UiSettings, GridContext, NitroCardContext, NitroCardAccordionContext)
- Native <script> hoisting for Turnstile, ExternalPluginLoader, GoogleAdsView
  (React 19 dedupes by src; removes manual document.head.appendChild +
  module-level promise caches)
- React Compiler enabled at build time via babel-plugin-react-compiler
  in vite.config.mjs (target: '19'), plus eslint-plugin-react-compiler
  in lint mode
- Global <ErrorBoundary> + <Suspense> in src/index.tsx using
  react-error-boundary, with LoadingView as fallback
- BackgroundsView migrated to use(promise) as a demonstrator pattern
  for Suspense-driven config loading
- ESLint react setting bumped 18.3.1 -> 19.2; legacy
  @typescript-eslint/ban-types replaced with no-restricted-types
  (the old rule was removed in @typescript-eslint v8)
- Refresh public/configuration/{asset-loader,bootstrap}.js to match
  current write-asset-loader.mjs output

Phase 3 (login forms -> useActionState/useFormStatus) deferred:
LoginView is 1623 lines with lockout + Turnstile + heartbeat
interleaving; safer as its own PR.

https://claude.ai/code/session_01GrR87LAqnAEyKG2ZbmQt5Q

eslint.config.mjs

@@ -1,6 +1,7 @@
 import typescriptEslintPlugin from "@typescript-eslint/eslint-plugin";
 import typescriptEslintParser from "@typescript-eslint/parser";
 import reactPlugin from "eslint-plugin-react";
+import reactCompilerPlugin from "eslint-plugin-react-compiler";
 import reactHooksPlugin from "eslint-plugin-react-hooks";
 import path from "path";
 import { fileURLToPath } from "url";
@@ -14,6 +15,7 @@ export default [
         plugins: {
             react: reactPlugin,
             "react-hooks": reactHooksPlugin,
+            "react-compiler": reactCompilerPlugin,
             "@typescript-eslint": typescriptEslintPlugin,
         },
         languageOptions: {
@@ -110,28 +112,24 @@ export default [
             '@typescript-eslint/no-unused-vars': [
                 'off'
             ],
-            '@typescript-eslint/ban-types': [
+            '@typescript-eslint/no-restricted-types': [
                 'error',
                 {
                     'types':
                     {
-                        'String': true,
-                        'Boolean': true,
-                        'Number': true,
-                        'Symbol': true,
-                        '{}': false,
-                        'Object': false,
-                        'object': false,
-                        'Function': false
-                    },
-                    'extendDefaults': true
+                        'String': { message: 'Use string instead', fixWith: 'string' },
+                        'Boolean': { message: 'Use boolean instead', fixWith: 'boolean' },
+                        'Number': { message: 'Use number instead', fixWith: 'number' },
+                        'Symbol': { message: 'Use symbol instead', fixWith: 'symbol' }
+                    }
                 }
             ],
-            'react/react-in-jsx-scope': 'off'
+            'react/react-in-jsx-scope': 'off',
+            'react-compiler/react-compiler': 'warn'
         },
         settings: {
             react: {
-                version: "18.3.1",
+                version: "19.2",
             },
         },
     },