Preserve identifiers and money

# Preserve product identifiers and monetary precision

This reproducible example maps supplier fields into an approved catalog contract.

Input fixture:

```csv
product_code,product_name,unit_price,currency,available
000123,Desk lamp,"19,90",EUR,12
000124,Reading light,"24,50",EUR,8
```

Validated output:

```jsonl
{"sku":"000123","title":"Desk lamp","price":"19.90","currency":"EUR","stock":12}
{"sku":"000124","title":"Reading light","price":"24.50","currency":"EUR","stock":8}
```

The approved mapping keeps the SKU as a string and explicitly declares the decimal separator. The entire file is checked before an accepted output is available. Changing column names requires a new approved profile.

Supported limits: flat CSV/JSONL, 10 MiB, 50,000 records. These synthetic fixtures demonstrate behavior; they do not establish customer ROI.