refac: add buffer module instead of Nodejs buffer

package.json

@@ -41,6 +41,7 @@
   },
   "dependencies": {
     "bech32": "^2.0.0",
+    "buffer": "^6.0.3",
     "create-hash": "^1.2.0",
     "secp256k1": "^5.0.0"
   },

src/encoding.spec.ts

@@ -3,6 +3,7 @@ import {
     decodeSilentPaymentAddress,
     encodeSilentPaymentAddress,
 } from './encoding';
+import { Buffer } from 'buffer';
 
 describe('Encoding', () => {
     describe.each([

src/encoding.ts

@@ -1,5 +1,6 @@
 import { bech32m } from 'bech32';
 import secp256k1 from 'secp256k1';
+import { Buffer } from 'buffer';
 
 export const encodeSilentPaymentAddress = (
     scanKey: Uint8Array,

src/outputs.ts

@@ -7,6 +7,7 @@ import {
 import { decodeSilentPaymentAddress } from './encoding.ts';
 import secp256k1 from 'secp256k1';
 import createHash from 'create-hash';
+import { Buffer } from 'buffer';
 
 export const createOutputs = (
     inputPrivateKeys: PrivateKey[],

src/scanning.spec.ts

@@ -1,5 +1,6 @@
 import { scanOutputs } from './scanning';
 import { LabelMap } from './interface';
+import { Buffer } from 'buffer';
 
 describe('Scanning', () => {
     it.each([

src/scanning.ts

@@ -2,6 +2,7 @@ import { serialiseUint32 } from './utility.ts';
 import { LabelMap } from './interface.ts';
 import secp256k1 from 'secp256k1';
 import createHash from 'create-hash';
+import { Buffer } from 'buffer';
 
 // Handle additional label-related logic
 const handleLabels = (

src/utility.ts

@@ -1,6 +1,7 @@
 import { Outpoint, PrivateKey } from './interface';
 import secp256k1 from 'secp256k1';
 import createHash from 'create-hash';
+import { Buffer } from 'buffer';
 
 export const hashOutpoints = (outpoints: Outpoint[]): Buffer => {
     const outpointBuffer = Buffer.concat(