[fix] Send response as buffer about koa HOT 4 CLOSED

import {PassThrough, Readable} from 'node:stream'

function * _generate() {
    yield 'test'
}

async function _stream(ctx) {
    const stream = Readable.from(_generate())
    ctx.type = 'application/octet-stream'
    ctx.response.set('content-disposition', 'attachment; filename="via_stream.txt"')
    ctx.body = stream.pipe(new PassThrough())
}

async function _json(ctx) {
    ctx.response.set('content-disposition', 'attachment; filename="via_json.json"')
    const _data = []
    for (const data of _generate()) {
        _data.push(data)
    }
    ctx.body = {
        type: 'Uint8Array',
        data: [...(new globalThis.TextEncoder().encode(_data.join('')))],
    }
}