feat: Add comprehensive backend validation, toast notifications, and Tokyo Night theme

- Backend: Add server-side validation with go-playground/validator/v10
- Frontend: Add toast notifications for API errors with @zerodevx/svelte-toast
- UI: Complete Tokyo Night theme redesign with modern animations
- Docs: Update COMPLETE_DOCUMENTATION.md and README.md with all enhancements
- Validation: Email format, password strength, and input sanitization
- UX: Real-time error feedback, loading states, and responsive design

backend/cmd/server/main.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"bookmann/internal/config"
+	"bookmann/internal/database"
+	"bookmann/internal/handlers"
+	"log"
+
+	"github.com/go-playground/validator/v10"
+	"github.com/golang-jwt/jwt/v5"
+	"github.com/labstack/echo/v4"
+	"github.com/labstack/echo/v4/middleware"
+)
+
+// CustomValidator wraps the go-playground validator
+type CustomValidator struct {
+	validator *validator.Validate
+}
+
+func (cv *CustomValidator) Validate(i interface{}) error {
+	return cv.validator.Struct(i)
+}
+
+func main() {
+	cfg := config.LoadConfig()
+
+	pool, err := database.NewConnection(cfg.DatabaseURL())
+	if err != nil {
+		log.Fatal("Failed to connect to database:", err)
+	}
+	defer pool.Close()
+
+	queries := database.New(pool)
+
+	e := echo.New()
+
+	// Set up validator
+	e.Validator = &CustomValidator{validator: validator.New()}
+
+	// Middleware
+	e.Use(middleware.Logger())
+	e.Use(middleware.Recover())
+	e.Use(middleware.CORS())
+
+	// Auth routes (no auth required)
+	auth := handlers.NewAuthHandler(queries, cfg.JWTSecret)
+	e.POST("/api/auth/register", auth.Register)
+	e.POST("/api/auth/login", auth.Login)
+
+	// JWT middleware for protected routes
+	jwtMiddleware := middleware.JWTWithConfig(middleware.JWTConfig{
+		SigningKey: []byte(cfg.JWTSecret),
+		ContextKey: "user",
+		SuccessHandler: func(c echo.Context) {
+			token := c.Get("user").(*jwt.Token)
+			claims := token.Claims.(jwt.MapClaims)
+			c.Set("user_id", claims["user_id"])
+		},
+	})
+
+	// Protected routes
+	protected := e.Group("/api", jwtMiddleware)
+	protected.GET("/auth/profile", auth.GetProfile)
+
+	// Routes
+	handlers.SetupRoutes(protected, queries)
+
+	// Serve static files
+	e.Static("/", "static")
+
+	// Start server
+	log.Printf("Starting server on port %s", cfg.ServerPort)
+	e.Logger.Fatal(e.Start(":" + cfg.ServerPort))
+}