fix(dashboard): Minor cleanup and improve text legibility (#7045)

**What**
- Cleans up some artifacts from the V1 -> V2 migrations.
- Removes the MedusaProvider from the root in favor of a plain QueryClient.
- Applies font styles to make the text in admin resemble designs in Figma more closely.

packages/admin-next/dashboard/src/components/layout/main-layout/main-layout.tsx

@@ -11,12 +11,12 @@ import {
 } from "@medusajs/icons"
 import { Avatar, Text } from "@medusajs/ui"
 import * as Collapsible from "@radix-ui/react-collapsible"
-import { useAdminStore } from "medusa-react"
 import { useTranslation } from "react-i18next"
 
+import { useStore } from "../../../hooks/api/store"
 import { Skeleton } from "../../common/skeleton"
-import { NavItem, NavItemProps } from "../nav-item"
-import { Shell } from "../shell"
+import { NavItem, NavItemProps } from "../../layout/nav-item"
+import { Shell } from "../../layout/shell"
 
 import extensions from "medusa-admin:routes/links"
 
@@ -46,7 +46,7 @@ const MainSidebar = () => {
 }
 
 const Header = () => {
-  const { store, isError, error } = useAdminStore()
+  const { store, isError, error } = useStore()
 
   const name = store?.name
   const fallback = store?.name?.slice(0, 1).toUpperCase()
@@ -135,8 +135,8 @@ const useCoreRoutes = (): Omit<NavItemProps, "pathname">[] => {
     },
     {
       icon: <ReceiptPercent />,
-      label: t("discounts.domain"),
-      to: "/discounts",
+      label: t("promotions.domain"),
+      to: "/promotions",
     },
     {
       icon: <CurrencyDollar />,