feat: Add API key middleware and update configuration to support API key validation

backend/internal/api/routes/router.go

@@ -4,11 +4,14 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/timetracker/backend/internal/api/handlers"
 	"github.com/timetracker/backend/internal/api/middleware"
+	"github.com/timetracker/backend/internal/config"
 )
 
 // SetupRouter configures all the routes for the API
-func SetupRouter(r *gin.Engine) {
+func SetupRouter(r *gin.Engine, cfg *config.Config) {
 	// Create handlers
+	// Apply API key middleware to all API routes
+	r.Use(middleware.APIKeyMiddleware(cfg))
 	userHandler := handlers.NewUserHandler()
 	activityHandler := handlers.NewActivityHandler()
 	companyHandler := handlers.NewCompanyHandler()