implement new invitation system

* fix comments on the frontend
* move jwt token service to its own module
* other fixes and updates

apps/server/src/helpers/nanoid.utils.ts

@@ -0,0 +1,5 @@
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const { customAlphabet } = require('fix-esm').require('nanoid');
+
+const alphabet = '0123456789abcdefghijklmnopqrstuvwxyz';
+export const nanoIdGen = customAlphabet(alphabet, 10);