Add integration test for the invoice search endpoint returning results ranked by relevance when query matches both title and description

[Chucks1093]

Summary

The invoice search endpoint should rank results with a title match higher than a description-only match. An integration test should seed invoices where the query appears in different fields and confirm the ranking order.

Scope

• Seed invoice A with the query in the title, invoice B with the query only in the description
• Call the search endpoint and assert invoice A appears before invoice B
• Seed invoice C with the query in both title and description and assert it ranks at or above invoice A
• Assert a query matching no invoices returns an empty array
• Assert the search is case-insensitive

Acceptance Criteria

• Title match ranked above description-only match
• Title+description match ranked at or above title-only match
• No match returns empty array
• Search is case-insensitive

ETA: 12 hours

---

Coordinate on Telegram