feat: implement credentials login

implements the credentials login functionality

src/lib/auth/login.ts

@@ -0,0 +1,27 @@
+'use server';
+
+import { z } from 'zod';
+import { loginSchema } from '@/lib/validation/user';
+import { signIn } from '@/auth';
+
+export async function loginAction(data: z.infer<typeof loginSchema>) {
+  try {
+    await signIn('credentials', {
+      ...data,
+      redirect: false,
+    });
+
+    return {
+      error: undefined,
+    };
+  } catch (error: unknown) {
+    if (error instanceof Error) {
+      return {
+        error: error.message.toString(),
+      };
+    }
+    return {
+      error: 'An unknown error occurred.',
+    };
+  }
+}