fix: address PR review - type consistency and runtime safety

- crypto.ts: widen aesEncrypWithIV params to Uint8Array for consistency
  with other AES helpers (Copilot review comment #1)
- noise-handler.ts: replace unsafe `as Buffer` type assertions with
  Buffer.from() for proper runtime conversion (Copilot review comment #2)

https://claude.ai/code/session_01Ffc5YrPuqv8N9SwEuSM8mr

src/Utils/crypto.ts

@@ -100,7 +100,7 @@ export function aesEncrypt(buffer: Buffer | Uint8Array, key: Uint8Array) {
 }
 
 // encrypt AES 256 CBC with a given IV
-export function aesEncrypWithIV(buffer: Buffer, key: Buffer, IV: Buffer) {
+export function aesEncrypWithIV(buffer: Buffer | Uint8Array, key: Uint8Array, IV: Uint8Array) {
 	const aes = createCipheriv('aes-256-cbc', key, IV)
 	return Buffer.concat([aes.update(buffer), aes.final()]) // prefix IV to the buffer
 }

src/Utils/noise-handler.ts

@@ -123,9 +123,9 @@ export const makeNoiseHandler = ({
 
 	const mixIntoKey = (data: Uint8Array) => {
 		const [write, read] = localHKDF(data)
-		salt = write as Buffer
+		salt = Buffer.from(write)
-		encKey = read as Buffer
+		encKey = Buffer.from(read)
-		decKey = read as Buffer
+		decKey = Buffer.from(read)
 		counter = 0
 	}