fix(deliveroo): handle UK API type differences

[Paul-Simpson]

Summary

Fixes JSON unmarshaling errors when using ordercli deliveroo history with UK accounts.

Problem

The UK Deliveroo API returns different types than expected:

• order_number: returned as int, model expected string
• total: returned as string (e.g., "19.64"), model expected *float64

This caused errors like:

json: cannot unmarshal number into Go struct field Order.orders.order_number of type string

Changes

• internal/deliveroo/model.go: Changed OrderNumber to int, Total/OriginalTotal to string
• internal/deliveroo/format.go: Updated Summary() to handle new types
• internal/deliveroo/format_test.go: Updated test fixtures

Testing

Tested with a real UK Deliveroo account:

$ ordercli deliveroo history --limit 3
id=50547707756 number=7756 status=DELIVERED restaurant=Sacro Cuore total=£19.64
id=50502752644 number=2644 status=DELIVERED restaurant=Thai Express total=£45.18
id=50500420138 number=138 status=DELIVERED restaurant=Sacro Cuore total=£37.95

Fixes #2