Implement expense tracking foundation for v1

src/app/add-expense/page.tsx

@@ -0,0 +1,22 @@
+import { ExpenseWorkspace } from "@/components/expense-workspace";
+import { CATEGORY_OPTIONS } from "@/lib/categories";
+
+export const metadata = {
+  title: "Add Expense | Monthy Tracker",
+};
+
+export default function AddExpensePage() {
+  return (
+    <div className="space-y-8">
+      <header className="max-w-2xl space-y-3">
+        <p className="text-sm font-semibold uppercase tracking-[0.28em] text-amber-700">Add Expense</p>
+        <h1 className="text-4xl font-semibold text-stone-950">Capture spending while it still feels fresh.</h1>
+        <p className="text-lg leading-8 text-stone-600">
+          This first slice focuses on fast local entry. Each saved expense appears immediately in your running history.
+        </p>
+      </header>
+
+      <ExpenseWorkspace categoryOptions={CATEGORY_OPTIONS.map((option) => ({ ...option }))} />
+    </div>
+  );
+}