refactor: top level dir + moved route

create a root directory entry in table for each user and move file browser under /directories/$id

packages/web/src/routes/_authenticated/_sidebar-layout.tsx

@@ -1,4 +1,5 @@
 import { createFileRoute, Outlet } from "@tanstack/react-router"
+import { useQuery as useConvexQuery } from "convex/react"
 import { SidebarInset, SidebarProvider } from "@/components/ui/sidebar"
 import { Toaster } from "@/components/ui/sonner"
 import { DashboardSidebar } from "@/dashboard/dashboard-sidebar"