[client/ui] Replace fyne UI with Wails (rename ui-wails to ui)

Removes the legacy fyne-based client/ui implementation and renames the
Wails replacement (client/ui-wails) to take its place at client/ui. Go
imports, frontend bindings, CI workflows, goreleaser configs and the
windows .syso icon path are updated to follow the rename.

client/ui/frontend/src/components/Card.tsx

@@ -0,0 +1,14 @@
+import { HTMLAttributes } from "react";
+import { cn } from "../lib/cn";
+
+export function Card({ className, ...rest }: HTMLAttributes<HTMLDivElement>) {
+  return (
+    <div
+      className={cn(
+        "rounded-lg border border-nb-gray-200 bg-white p-4 dark:border-nb-gray-800 dark:bg-nb-gray-925",
+        className,
+      )}
+      {...rest}
+    />
+  );
+}