feat(app): add environment import/export and sidebar footer info

- add environment import/export API endpoints and client integration

- add environment export actions and toolbar import/export buttons in UI

- move theme switcher to sidebar bottom and show root package version

- switch snippet card menu icon to cog for consistent options affordance

server/package.json

@@ -1,5 +1,6 @@
 {
   "name": "liqa-server",
+  "version": "1.0.0",
   "main": "index.js",
   "scripts": {
     "build": "nest build",