Deploying larger compiled packages can fail during base64 encoding

## Summary

Deploying a compiled contract can fail before `useDeploy()` is called when the compiled package is large enough.

`ContractList` converts `contract.packageBytes` to base64 with:

```ts
btoa(String.fromCharCode(...contract.packageBytes))
```

Spreading a large `Uint8Array` into `String.fromCharCode()` is limited by the JavaScript engine's maximum argument count. Once the compiled package crosses that threshold, the click handler throws synchronously with `RangeError: Maximum call stack size exceeded` and the deploy flow never starts.

## Repro

This is the same conversion pattern used by the deploy button:

```sh
node -e "const b=new Uint8Array(200000); String.fromCharCode(...b)"
```

It fails with:

```text
RangeError: Maximum call stack size exceeded
```

## Impact

A contract can compile successfully and still be impossible to deploy from the UI solely because its `.masp` package is too large for the spread call. The deploy hook already accepts base64, so this is only an encoding issue in the UI boundary.

## Suggested fix

Encode the `Uint8Array` in chunks, or move a safe `uint8ArrayToBase64()` helper into a shared utility and use it from `ContractList`.

查看 ContractList 元件中 contract.packageBytes 被轉換為 base64 的地方。問題在於使用了 String.fromCharCode(...contract.packageBytes)。尋找或建立一個用於安全地對大型 Uint8Array 進行 base64 編碼的實用函數，或許可以放在共用的 utils 檔案中。透過模擬大型套件的部署來測試修復。

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