Fix: replace @/* path alias with relative imports for Docker compat

Vite's path alias resolution worked locally but consistently failed in
the Docker stage with "Could not load /web/src/lib/utils ... ENOENT"
even after fixing __dirname for ESM. Some interaction between act/buildx
and Vite's resolver around tsconfig paths. Relative imports sidestep the
issue entirely and are explicit about the dependency direction.

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

web/src/components/ui/input.tsx

@@ -1,5 +1,5 @@
 import * as React from "react";
-import { cn } from "@/lib/utils";
+import { cn } from "../../lib/utils";
 
 const Input = React.forwardRef<HTMLInputElement, React.InputHTMLAttributes<HTMLInputElement>>(
   ({ className, type, ...props }, ref) => {