Initial fullstack project setup with Next.js 15, Gin, PostgreSQL and Docker Compose

- Frontend: Next.js 15 (App Router), Auth.js v5, shadcn/ui, MagicUI
- Backend: Go + Gin + GORM with layered architecture
- Auth: Local credentials login with optional Keycloak OAuth binding
- Admin: RBAC user management for admin role
- Dev: Docker Compose with hot reload for both frontend and backend
- Docker: 3-service orchestration (frontend, backend, postgres)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/internal/middleware/rbac.go

@@ -0,0 +1,18 @@
+package middleware
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+func RequireRole(role string) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		userRole := c.GetString("userRole")
+		if userRole != role {
+			c.AbortWithStatusJSON(http.StatusForbidden, gin.H{"error": "forbidden"})
+			return
+		}
+		c.Next()
+	}
+}