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

src/components/floorplan-editor/FloorplanEditorContext.tsx

@@ -1,4 +1,4 @@
-import { createContext, Dispatch, FC, ProviderProps, SetStateAction, useContext } from 'react';
+import { createContext, Dispatch, FC, SetStateAction, useContext } from 'react';
 import { IFloorplanSettings } from '@nitrots/nitro-renderer';
 import { IVisualizationSettings } from '@nitrots/nitro-renderer';
 
@@ -29,6 +29,6 @@ const FloorplanEditorContext = createContext<IFloorplanEditorContext>({
     areaInfo: { total: 0, walkable: 0 }
 });
 
-export const FloorplanEditorContextProvider: FC<ProviderProps<IFloorplanEditorContext>> = props => <FloorplanEditorContext.Provider { ...props } />;
+export const FloorplanEditorContextProvider: FC<{ value: IFloorplanEditorContext; children?: React.ReactNode }> = props => <FloorplanEditorContext { ...props } />;
 
 export const useFloorplanEditorContext = () => useContext(FloorplanEditorContext);