feat(desktop): add structured desktop chat app

Introduce the Electron desktop app with a split app/chat/settings structure and shared nanostore state so UI areas own their state instead of routing it through the root.

apps/desktop/src/components/ui/input.tsx

@@ -0,0 +1,21 @@
+import * as React from 'react'
+
+import { cn } from '@/lib/utils'
+
+function Input({ className, type, ...props }: React.ComponentProps<'input'>) {
+  return (
+    <input
+      className={cn(
+        'h-9 w-full min-w-0 rounded-md border border-input bg-transparent px-3 py-1 text-base shadow-xs transition-[color,box-shadow] outline-none selection:bg-primary selection:text-primary-foreground file:inline-flex file:h-7 file:border-0 file:bg-transparent file:text-sm file:font-medium file:text-foreground placeholder:text-muted-foreground disabled:pointer-events-none disabled:cursor-not-allowed disabled:opacity-50 md:text-sm dark:bg-input/30',
+        'focus-visible:border-ring focus-visible:ring-[0.1875rem] focus-visible:ring-ring/50',
+        'aria-invalid:border-destructive aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40',
+        className
+      )}
+      data-slot="input"
+      type={type}
+      {...props}
+    />
+  )
+}
+
+export { Input }