clear button cant clear error msg & feat: add setting dialog and add accesscode (#77)

* fix: clear button cant clear error msg

* new: add setting dialog and add accesscode

* fix: address review feedback - dark mode, types, formatting

* feat: only show Settings button when access code is required

* refactor: rename ACCESS_CODES to ACCESS_CODE_LIST

---------

Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>

app/api/config/route.ts

@@ -0,0 +1,9 @@
+import { NextResponse } from "next/server";
+
+export async function GET() {
+  const accessCodes = process.env.ACCESS_CODE_LIST?.split(',').map(code => code.trim()).filter(Boolean) || [];
+
+  return NextResponse.json({
+    accessCodeRequired: accessCodes.length > 0,
+  });
+}