Settlements vs GL export: two distinct workflows

# Instructions — Settlements vs GL Export: two distinct workflows

## ⚠️ Fundamental rule

There are **two independent export workflows** in Spendesk:

| Workflow | Object | Tool | When to use it |
|----------|-------|-------|-----------------|
| **Cash clearance** | Cash movements (card transactions + transfers) | `get_settlements` | Bank reconciliation |
| **GL export** | Invoices/expenses to record in accounting | `get_payables` + `bookkeepingStatus` | ERP export |

A settlement with `state=exported` = this cash movement has been exported to an accounting system.
A payable with `bookkeepingStatus=exported` = this invoice/expense has been exported to the ERP.
**These two exports are independent** — a settlement can be exported without the related payable being exported, and vice versa.

## Use case 1 — Bank reconciliation (use settlements)

### Step 1

Call `get_settlements` with:
```json
{
  "companyId": "...",
  "clearedFrom": "YYYY-MM-DDT00:00:00.000Z",
  "clearedTo": "YYYY-MM-DDT23:59:59.999Z",
  "state": ["created"]
}
```
`state=created` = cleared in Spendesk, not yet exported → what's left to reconcile.

### Step 2 — Currency handling (CRITICAL)

Each settlement is in the transaction's currency (`currency`), not in the functional currency.
- Use `billingAmount` (in `billingCurrency`, typically the functional currency) for totals
- **Never sum `amount` across currencies**

Example observed:
- USD card settlement: `amount=94.80 USD`, `billingAmount=81.57 EUR`
- GBP wire transfer settlement: `amount=34,530.67 GBP`, `billingAmount=40,089.14 EUR`
→ Summing 94.80 + 34530.67 makes no sense. Summing 81.57 + 40089.14 = 40,170.71 EUR ✅

### Step 3

For each settlement, the field `allocations[].payableId` lets you look up the related payable via `get_payable_by_id`.

## Use case 2 — ERP / GL export (use payables)

To prepare an accounting export, **do not use settlements**:

Call `get_payables` with `bookkeepingStatus=["toExport"]`.

→ See skill `s10-factures-a-exporter-comptabilite`.

## Settlement states

| State | Meaning |
|-------|-------------|
| `created` | Cleared in Spendesk, not yet exported to the ERP |
| `exported` | Sent to the ERP (settlement record) |
| `failedToExport` | Export attempt failed → needs investigation |

## Example prompt

- "Which bank movements were cleared in June but not yet exported?" → `state=created`
- "Reconcile this week's card transactions" → `get_settlements` + `clearedFrom/To`
- "Prepare the monthly accounting export" → `get_payables` + `bookkeepingStatus=toExport`