feat(dashboard,admin-vite-plugin): Add product zones and fix zone change effect (#7427)

**What**
- Adds injection zones to the product domain.
- Fixes an issue where changing the `zone` in a widget config to another valid widget would not trigger a HMR event.
- Fixes an issue where UI Routes would not work in production.

packages/admin-next/dashboard/vite.config.mts

@@ -1,26 +1,33 @@
 import inject from "@medusajs/admin-vite-plugin"
 import react from "@vitejs/plugin-react"
-import { defineConfig } from "vite"
-
-const BASE = "/"
-const BACKEND_URL = "http://localhost:9000"
-
-console.log(inject)
+import { defineConfig, loadEnv } from "vite"
 
 // https://vitejs.dev/config/
-export default defineConfig({
-  plugins: [
-    react(),
-    inject({
-      debug: true,
-      sources: ["/Users/kasperkristensen/work/v2-server/src/admin"],
-    }),
-  ],
-  define: {
-    __BASE__: JSON.stringify(BASE),
-    __BACKEND_URL__: JSON.stringify(BACKEND_URL),
-  },
-  server: {
-    open: true,
-  },
+export default defineConfig(({ mode }) => {
+  const env = loadEnv(mode, process.cwd())
+
+  const BASE = env.VITE_MEDUSA_BASE || "/"
+  const BACKEND_URL = env.VITE_MEDUSA_BACKEND_URL || "http://localhost:9000"
+
+  /**
+   * Add this to your .env file to specify the project to load admin extensions from.
+   */
+  const MEDUSA_PROJECT = env.VITE_MEDUSA_PROJECT || null
+  const sources = MEDUSA_PROJECT ? [MEDUSA_PROJECT] : []
+
+  return {
+    plugins: [
+      react(),
+      inject({
+        sources,
+      }),
+    ],
+    define: {
+      __BASE__: JSON.stringify(BASE),
+      __BACKEND_URL__: JSON.stringify(BACKEND_URL),
+    },
+    server: {
+      open: true,
+    },
+  }
 })