feat(server): add request ID middleware

Add request ID middleware to trace requests through the system. The middleware checks for existing X-Request-ID headers, generates a new UUID if not present, and sets the ID in both request/response headers and Gin context.

cmd/server/main.go

@@ -121,6 +121,7 @@ func main() {
 
 	// 5. Setup Gin Router
 	r := gin.Default()
+	r.Use(middleware.RequestID())
 
 	// CORS Middleware
 	r.Use(func(c *gin.Context) {