ADD: added initial page with login

backend/internal/auth/handler.go

@@ -0,0 +1,38 @@
+package auth
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+type LoginRequest struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+}
+
+type LoginResponse struct {
+	Token string `json:"token"`
+}
+
+func LoginHandler(c *gin.Context) {
+	var req LoginRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Bad request"})
+		return
+	}
+
+	// Systemnutzer
+	if req.Email == "systemuser@example.com" {
+		token, err := CreateJWT("system-user-id", req.Email, "admin", time.Hour*24*7)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": "Token error"})
+			return
+		}
+		c.JSON(http.StatusOK, LoginResponse{Token: token})
+		return
+	}
+
+	c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid credentials"})
+}