feat: implement comprehensive logging standards (#536)

[soterika]

• Add AppLoggerService: structured JSON logs, correlation IDs, NestJS ConsoleLogger extension, convenience methods (logRequest, logEvent, logQuery)
• Add redaction.util: recursive sensitive-data redaction for 30+ key patterns (password, token, secret, authorization, jwt, pin, cvv, etc.)
• Add LoggingInterceptor: global HTTP request/response logger with duration, status code, and correlation ID echo header
• Add LoggingMiddleware: lightweight middleware to propagate correlation ID to response headers
• Add LoggingModule (@global): registers AppLoggerService, interceptor, and middleware; imported once in AppModule
• Add 87 unit tests across 3 suites covering all acceptance criteria
• Add docs/logging.md: usage guide, log level table, configuration, integration examples

Closes #536