Optimize database queries for user tip lookup

[Mosas2000]

Type: Performance
Component: Backend
Priority: High

Description

The /api/tips/user/:address endpoint performs full table scans when looking up tips by sender or recipient address. Add database indexes to improve query performance.

Current Behavior

• Full table scan for user address lookups
• Slow response times with large datasets
• High database CPU usage

Expected Behavior

• Indexed queries on sender and recipient fields
• Sub-100ms response times
• Reduced database load

Acceptance Criteria

• Add database indexes for sender and recipient columns
• Add migration script for existing deployments
• Benchmark query performance before and after
• Update deployment documentation
• No breaking changes to API