feat: QR-Custom Payment + mode webhook secret GOWA

- tabel custom_qr_payments, service, halaman admin + publik share
- kode unik 20 menit, warning bila bayar setelah batas, manual pay/accept/reject
- webhook payment-notif mencocokkan nominal custom
- menu sidebar QR-Custom Payment
- GOWA secret: auto generate (locked) / manual (simpan lalu locked, ubah)
- versi 0.6.0

README.md

@@ -11,7 +11,7 @@
 
 <p align="center">
   <img src="https://img.shields.io/badge/lisensi-ISC-ADFF2F" alt="Lisensi: ISC">
-  <img src="https://img.shields.io/badge/versi-0.5.20_copy--secret-ADFF2F" alt="Versi 0.5.20 (copy-secret)">
+  <img src="https://img.shields.io/badge/versi-0.6.0_qr--custom-ADFF2F" alt="Versi 0.6.0 (qr-custom)">
   <img src="https://img.shields.io/badge/Node.js-%E2%89%A520-339933" alt="Node.js >= 20">
   <img src="https://img.shields.io/badge/docker-ready-2496ED?logo=docker&logoColor=white" alt="Docker">
   <a href="https://demo-openisp.oxpoe.xyz"><img src="https://img.shields.io/badge/demo-live-ADFF2F?logo=googlechrome&logoColor=black" alt="Demo"></a>