[Award routes] SPIKE: Validate opportunity-to-award linking between Grants.gov and USASpending data

[laurabelinfante]

Summary

Confirm that Grants.gov opportunity records can be reliably linked to their resulting USASpending award records, using static snapshots of both datasets. Findings feed the awards reference implementation scope and de-risk next quad's lifecycle metric; if linking proves harder than expected, the metric can switch.

Acceptance criteria

• Opportunity-to-award linking is tested with sample data from both sources
• Findings and a recommended approach are documented