Update logging to use Pino

[edeNFed]

Logging across the coupon and mail NodeJS services, and the webapp frontend, was migrated from console.log to pino.

• Structured JSON logging was implemented, replacing console.log statements.
• Dedicated logger utilities were created: coupon/logger.js, mail/logger.ts, and webapp/utils/logger.js.
• pino-http was integrated into coupon/app.js for automatic HTTP request/response logging.
• Enhanced logging was added for:
  • HTTP request/response timing and details.
  • External service calls (e.g., membership service).
  • Kafka producer and consumer operations, including message processing.
  • Frontend API calls with timing and error tracking.
• All OpenTelemetry-specific code and dependencies were removed. This ensures the applications produce pure, agent-agnostic structured logs, allowing correlation with traces to be handled externally by a runtime observability agent.