Add fast-crud integration with Element Plus demo

Integrate the fast-crud framework with Element Plus adapter, global
component registration, request transform utilities, and a demo CRUD
page with router entry.

src/router/index.ts

@@ -99,6 +99,14 @@ export const constantRoutes: RouteRecordRaw[] = [
           keepAlive: true
         }
       },
+      {
+        path: "fast-crud",
+        component: () => import("@/pages/demo/fast-crud/index.vue"),
+        name: "FastCrud",
+        meta: {
+          title: "Fast Crud"
+        }
+      },
       {
         path: "level2",
         component: () => import("@/pages/demo/level2/index.vue"),