Implement Server-Side Evidence Uniqueness Validation

[tlxxxsracer]

Implement Server-Side Evidence Uniqueness Validation

Original Task

Implement Server-Side Evidence Uniqueness Validation

Summary of Changes

Added comprehensive server-side validation to prevent duplicate evidence submissions by implementing a robust uniqueness check with caching and detailed logging.

Acceptance Criteria

• Create a uniqueness validation method that checks against existing evidence records
• Implement a caching layer to quickly reject duplicate submissions
• Log all duplicate submission attempts with detailed error information
• Return a 409 Conflict HTTP status for duplicate submissions
• 100% unit test coverage for uniqueness validation logic
• Uniqueness check completes in less than 50ms

Tests

• Verify uniqueness validation method works correctly
• Check caching layer prevents duplicate submissions
• Ensure detailed logging for duplicate submission attempts
• Confirm 409 Conflict status is returned for duplicates
• Validate performance of uniqueness check is under 50ms
• Verify comprehensive unit test coverage