Update Order model to include rating information

[coderabbitai]

Description

Currently, the trade details screen uses NostrEvent to extract rating information (totalRating, totalReviews, days) as a temporary measure. This approach was implemented in PR #225 to display real user reputation data.

TODO

Update the Order model to include rating information directly, eliminating the need to use NostrEvent for this purpose.

Context

• File: lib/features/trades/screens/trade_detail_screen.dart
• Current implementation extracts rating from NostrEvent.rating property
• This is a temporary solution until the Order model is enhanced

Acceptance Criteria

• Add rating fields to the Order model (totalRating, totalReviews, days)
• Update the trade details screen to use Order model rating data instead of NostrEvent
• Ensure backward compatibility during the transition
• Update any related tests

References

• Original PR: Show user's reputation real data on trade details #225
• Comment: Show user's reputation real data on trade details #225 (comment)