feat: setup gateway routing, security bypass and headers propagation for wallet

Objective The goal of this PR is to finalize the connectivity between the Gateway and the wallet-ledger-service, ensuring proper header propagation (X-User-Id) and handling security configurations for integration testing.

Key Changes Routing & Rewrite: Configured GatewayConfig to redirect /api/wallet/** to the versioned path /api/v1/wallet/** of the microservice.

WebFlux Security: Implemented SecurityConfig with a temporary exception (permitAll) on wallet endpoints to facilitate integration tests (marked with a TODO for production).

CORS: Maintained configuration in application.yml to authorize requests from the frontend (http://localhost:3000).

Integration Tests: Added WalletUserIdPropagationIT to validate that the X-User-Id header is correctly transmitted to the downstream service.

Dependencies: Added spring-boot-starter-security and mockwebserver (test scope) to the pom.xml.

Tests Performed Verified routing through the Gateway on port 8080.

Tested X-User-Id header propagation.

Validated frontend connectivity (CORS).