chore: добавить SLM-каркас admin

- добавлен app entrypoint, main layout и dashboard screen\n- настроены алиасы SLM-слоёв и PostCSS для CSS Modules\n- перенесены глобальные стили в shared/styles

apps/admin/package.json

@@ -10,14 +10,19 @@
     "typecheck": "tsc -b"
   },
   "dependencies": {
+    "clsx": "^2.1.1",
     "react": "^19.2.5",
     "react-dom": "^19.2.5"
   },
   "devDependencies": {
+    "@csstools/postcss-global-data": "^4.0.0",
     "@types/node": "^24.12.2",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^6.0.1",
+    "autoprefixer": "^10.5.0",
+    "postcss-custom-media": "^12.0.1",
+    "postcss-nesting": "^14.0.0",
     "typescript": "^5.9.3",
     "vite": "^8.0.10"
   }