Fix the ParcelDesk SDK quickstart

[ZIJ]

The scheduled quickstart check reproduced a failure in docs/quickstart.md against the released ParcelDesk SDK. ParcelDesk is a deliberately constructed example fixture.

Diagnosis: released parceldesk-sdk-2.0.0.tgz's client.orders.list() resolves to a paged response object { items, nextCursor } (confirmed in the installed package's src/index.js and src/index.d.ts: Promise<OrderPage> where OrderPage = { items: Order[]; nextCursor: string | null }). The guide's snippet assigned the raw resolved value to orders and called .map() directly on it, which throws because the value is a plain object, not an array. Fix: destructure items from the resolved page (const { items: orders } = await client.orders.list({ limit: 2 });) so .map() operates on the actual array. No other guide content, SDK release URL, version, or expected output changed.

Verification command, run before and after the documentation change in separate fresh projects:

node scripts/verify-quickstart.mjs docs/quickstart.md

Before:

Command: node scripts/verify-quickstart.mjs docs/quickstart.md (exit 1)
Guide: docs/quickstart.md
SDK: https://github.com/diggerhq/opencomputer-example-quickstart-check/releases/download/sdk-v2.0.0/parceldesk-sdk-2.0.0.tgz
file://<quickstart>/quickstart.mjs:8
    .map((order) => `${order.id}: ${order.customer} ($${(order.totalCents / 100).toFixed(2)})`)
     ^

TypeError: orders.map is not a function
    at file://<quickstart>/quickstart.mjs:8:6

Node.js v22.23.2
QUICKSTART FAILED

Separately, in <temp-project>, ran:
npm install --ignore-scripts --no-audit --no-fund https://github.com/diggerhq/opencomputer-example-quickstart-check/releases/download/sdk-v2.0.0/parceldesk-sdk-2.0.0.tgz
(exit 0, 1 package added)

Inspected <temp-project>/node_modules/@parceldesk/sdk/src/index.js and index.d.ts:
list(options?: ListOrdersOptions): Promise<OrderPage>
where OrderPage = { items: Order[]; nextCursor: string | null }
confirming client.orders.list() resolves to an object with an `items` array, not a bare array.

After:

Command: node scripts/verify-quickstart.mjs docs/quickstart.md (exit 0)
Guide: docs/quickstart.md
SDK: https://github.com/diggerhq/opencomputer-example-quickstart-check/releases/download/sdk-v2.0.0/parceldesk-sdk-2.0.0.tgz
ord_1042: Ada Lovelace ($49.00)
ord_1043: Grace Hopper ($125.00)
QUICKSTART PASSED — output matches the guide.

Only docs/quickstart.md is changed. The SDK release and expected result are preserved.