Invoices ready for accounting export

# Instructions — Invoices ready to export to accounting

## ⚠️ Critical anti double-posting rule

The three `bookkeepingStatus` statuses represent the accounting cycle:
- `toPrepare`: received in Spendesk, not yet reviewed
- `toExport`: reviewed and ready to send to the ERP → **this is what we want here**
- `exported`: already sent to the ERP → **DO NOT include** to avoid double-posting

This status is distinct from the payment status (`paymentStatus=toPay/paid`) — an invoice can be ready to export without being paid yet.

## Step 1 — Identify the company

Call `list_companies`.

## Step 2 — Retrieve the toExport payables

Call `get_payables` with:
```json
{
  "companyId": "...",
  "filters": {
    "field": "bookkeepingStatus",
    "operator": "=",
    "value": ["toExport"]
  }
}
```

Paginate if `hasNextPage=true`.

## Step 3 — Optional: filter by period

If the user wants only the payables for a given period, combine with a `payableDate` filter:
```json
{
  "operator": "and",
  "subfilters": [
    { "field": "bookkeepingStatus", "operator": "=", "value": ["toExport"] },
    { "field": "payableDate", "operator": "between", "value": { "from": "...", "to": "..." } }
  ]
}
```

## Step 4 — Present the results

Display:
- Total number of payables ready to export
- Total in functional currency (sum `functionalAmount.amount / 10^precision`)
- List with: date, supplier/employee, type (invoicePurchase/expenseClaim/etc.), amount, invoice number
- Group by `payableType` to make the ERP export easier

## Note on toPrepare

`toPrepare` payables are not ready yet — they must first be reviewed in Spendesk before moving to `toExport`. To see them: same call with `value: ["toPrepare"]`.

## Example prompts

- "Which invoices are ready to export to accounting?"
- "Give me the list of toExport payables for my monthly export"