Internationalize validation error message

Replaced hardcoded "Validation failed" message with translated
version from language files:
- Updated userProfileActions.ts to use t("validation-failed")
- Added translations in English and Croatian
- Reordered general-error div in AccountForm for better layout

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/lib/actions/userProfileActions.ts

@@ -77,7 +77,7 @@ export const updateUserProfile = withUser(async (user: AuthenticatedUser, prevSt
     if (!validatedFields.success) {
         return {
             errors: validatedFields.error.flatten().fieldErrors,
-            message: "Validation failed",
+            message: t("validation-failed"),
             success: false,
         };
     }