TS 5.7+ ArrayBuffer drift: cast where ArrayBufferLike leaked

TypeScript 5.7 split ArrayBuffer / SharedArrayBuffer at the type level
(ArrayBuffer now exposes resizable/transfer/detached etc; SharedArrayBuffer
doesn't), and parametrized the typed-array constructors so plain
Uint8Array became Uint8Array<ArrayBufferLike>.

The renderer never uses SharedArrayBuffer, so this is type-level only —
narrowing back to ArrayBuffer at the boundaries:

- BinaryReader.readBytes() / .toArrayBuffer() return the underlying
  DataView buffer; cast to ArrayBuffer.
- BinaryWriter.getBuffer() same shape.
- WsSessionCrypto.randomNonce() now returns Uint8Array<ArrayBuffer>
  (it's always backed by a plain ArrayBuffer); aesGcmEncrypt/Decrypt
  nonce parameter retyped accordingly so SubtleCrypto.encrypt accepts
  it as BufferSource.
- ArrayBufferToBase64 now accepts Uint8Array | ArrayBufferLike directly
  (pako/inflate hands back Uint8Array<ArrayBuffer> which the old
  ArrayBuffer-only signature rejected).

packages/communication/src/crypto/WsSessionCrypto.ts

@@ -38,17 +38,17 @@ export async function deriveAesKey(sharedSecret: ArrayBuffer): Promise<CryptoKey
     );
 }
 
-export async function aesGcmEncrypt(key: CryptoKey, nonce: Uint8Array, plaintext: ArrayBuffer): Promise<ArrayBuffer>
+export async function aesGcmEncrypt(key: CryptoKey, nonce: Uint8Array<ArrayBuffer>, plaintext: ArrayBuffer): Promise<ArrayBuffer>
 {
     return window.crypto.subtle.encrypt({ name: 'AES-GCM', iv: nonce, tagLength: GCM_TAG_LEN * 8 }, key, plaintext);
 }
 
-export async function aesGcmDecrypt(key: CryptoKey, nonce: Uint8Array, ciphertextWithTag: ArrayBuffer): Promise<ArrayBuffer>
+export async function aesGcmDecrypt(key: CryptoKey, nonce: Uint8Array<ArrayBuffer>, ciphertextWithTag: ArrayBuffer): Promise<ArrayBuffer>
 {
     return window.crypto.subtle.decrypt({ name: 'AES-GCM', iv: nonce, tagLength: GCM_TAG_LEN * 8 }, key, ciphertextWithTag);
 }
 
-export function randomNonce(): Uint8Array
+export function randomNonce(): Uint8Array<ArrayBuffer>
 {
     const n = new Uint8Array(NONCE_LEN);
     window.crypto.getRandomValues(n);