initial: mirror of @fn_library from fn_registry

75 components + DESIGN_SYSTEM.md + sync script.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/loading_overlay.tsx

@@ -0,0 +1,26 @@
+import { LoadingOverlay } from '@mantine/core'
+
+interface FnLoadingOverlayProps {
+  visible: boolean
+  loaderSize?: number | string
+  overlayBlur?: number
+  overlayOpacity?: number
+}
+
+function FnLoadingOverlay({
+  visible,
+  loaderSize,
+  overlayBlur = 2,
+  overlayOpacity = 0.5,
+}: FnLoadingOverlayProps) {
+  return (
+    <LoadingOverlay
+      visible={visible}
+      loaderProps={loaderSize ? { size: loaderSize } : undefined}
+      overlayProps={{ blur: overlayBlur, backgroundOpacity: overlayOpacity }}
+    />
+  )
+}
+
+export { FnLoadingOverlay }
+export type { FnLoadingOverlayProps }