ci: merge biome configs to fix nested config error

Root and services/frontend each had a biome.json causing Biome to
error on nested configuration. Merged frontend-specific rules and
domains (next, react) into root biome.json, removed nested config.

services/frontend/components.json

@@ -1,25 +0,0 @@
-{
-  "$schema": "https://ui.shadcn.com/schema.json",
-  "style": "base-nova",
-  "rsc": true,
-  "tsx": true,
-  "tailwind": {
-    "config": "",
-    "css": "src/app/globals.css",
-    "baseColor": "neutral",
-    "cssVariables": true,
-    "prefix": ""
-  },
-  "iconLibrary": "lucide",
-  "rtl": false,
-  "aliases": {
-    "components": "@/components",
-    "utils": "@/lib/utils",
-    "ui": "@/components/ui",
-    "lib": "@/lib",
-    "hooks": "@/hooks"
-  },
-  "menuColor": "default",
-  "menuAccent": "subtle",
-  "registries": {}
-}