docs: update README preview image

refactor: redesign home page and inherit from BasePage

refactor: redesign signup page and inherit from BasePage

refactor: redesign login page and inherit from BasePage

Add BasePage for shared layout and navigation helpers"

Change app name to YOUR APP NAME

Update README.md with utils.py documentation

Update README.md with app preview

Add app preview screenshots

Upgrade flet-model to version 0.1.5

Install aiohttp

Create async and sync server availability check helper

Create check auth async and sync helpers to check if user logged in or not

Create sync and async request building functions in utils

Update README