feat: add risk evaluation history endpoint

[Hallab7]

Implement GET /api/risk/history/:walletAddress endpoint to retrieve
historical risk evaluations for a given wallet address, including risk
scores, credit limits, timestamps, and optional evaluation inputs.

Changes:

• Add RiskEvaluationRepository with create() and findByWalletAddress()
• Implement getRiskHistory() service function with wallet validation
• Add GET /api/risk/history/:walletAddress route with unified response format
• Update OpenAPI documentation with complete endpoint specification
• Fix wallet address validation regex (55 chars total, not 56)
• Add support for future risk engine outputs via flexible inputs field

Features:

• Returns evaluations ordered by date (newest first)
• Proper error handling with 400 status for invalid addresses
• Secure parameterized queries to prevent SQL injection
• Database connection lifecycle management (connect/end)
• Risk level calculation (low < 40, medium 40-69, high >= 70)

Testing:

• 57 new tests across repository, service, and route layers
• 100% coverage on new code (repository, service function, endpoint)
• All tests passing

How to test:

Run all new tests

npm test -- src/db/riskEvaluationRepository.test.ts src/test/riskHistoryRoute.test.ts src/test/riskHistoryService.test.ts

Run with coverage report

npm test -- --coverage src/db/riskEvaluationRepository.test.ts src/test/riskHistoryRoute.test.ts src/test/riskHistoryService.test.ts

Files changed:

• src/db/riskEvaluationRepository.ts (new)
• src/db/riskEvaluationRepository.test.ts (new)
• src/services/riskService.ts (enhanced)
• src/routes/risk.ts (enhanced)
• src/test/riskHistoryRoute.test.ts (new)
• src/test/riskHistoryService.test.ts (new)
• docs/openapi.yaml (updated)
• src/openapi.yaml (updated)
• vitest.config.ts (updated coverage config)
• RISK_HISTORY_IMPLEMENTATION.md (new)

Closes #24

[greatest0fallt1me]

@Hallab7 Can you resolve the conflicts?

[Hallab7]

@greatest0fallt1me conflict resolved.