Inactive purchase orders audit

# Audit of inactive purchase orders

## Purpose
Identify open purchase orders (POs) that have had no recent invoicing activity. Inactive POs tie up budget commitments, distort projections, and signal undelivered goods or suppliers to follow up with.

## Instructions

### Step 1 — Retrieve all open POs
```
Call get_purchase_orders with status=open (or pending, active).
For each PO: note id, supplierId, budgetAmount, invoicedAmount,
currency, startDate, expectedDeliveryDate, description.

Calculate for each PO:
  remainingAmount = budgetAmount - invoicedAmount
  commitmentRate = invoicedAmount / budgetAmount × 100
  age = today - startDate (in days)
```

### Step 2 — Identify inactive POs
```
A PO is "inactive" if no invoice has been received in the last X days.

For each PO:
  Call get_payables with:
    - supplierId of the PO
    - firstCreatedAt > startDate of the PO
  If no recent payable (last 60 days) → PO potentially inactive

Inactivity categories:
  🔴 Inactive > 90 days: no invoice for 3 months
  🟡 Inactive 60-90 days: to monitor
  ⚠️ Expired PO: expectedDeliveryDate passed but not closed
  📦 New unused PO: startDate < 30 days, commitmentRate = 0%
```

### Step 3 — Resolve the suppliers involved
```
For inactive and expired POs:
  Call get_supplier_by_id for each unique supplierId.
  Retrieve: name, email (for potential follow-up).
```

### Step 4 — Calculate the budget impact
```
For each category:
  Total locked commitments = sum of remainingAmounts of inactive POs
  This budget commitment is fictitious and can be released if the POs are closed.
```

### Step 5 — Inactive POs report
```
Present:
1. Overview:
   Total open POs: X | Active: X | Inactive: X
   Locked budget commitment: X€

2. 🔴 Inactive POs > 90d:
   Supplier | PO amount | Remaining | Last payment | Age | Action

3. ⚠️ Expired POs (date passed, not closed):
   Supplier | PO amount | Expiration date | Remaining

4. 🟡 POs 60-90d with no activity:
   Supplier | PO amount | Remaining

5. Recommendations:
   - Close POs inactive > 90d
   - Follow up with suppliers on expired POs
   - Check for undelivered goods not yet invoiced
```

## Points of attention
- PO → Invoice matching is done by supplierId, not by direct PO reference (MCP limitation)
- A supplier may have several active POs — inactivity may be normal if another order is in progress
- Never close a PO without checking with the requester that delivery has indeed been abandoned

## Example prompts
- "Which purchase orders are open with no activity for more than 3 months?"
- "Audit my open POs and identify which ones to close"
- "How much budget is locked up in inactive POs?"