Add help/legal screen ⚖️

[opatry]

Add a screen to present various information about the app

• App version (text)
• Website (link to https://opatry.github.io/taskfolio)
• Github (link to https://github.com/opatry/taskfolio)
• Privacy Policy (link to https://opatry.github.io/taskfolio/privacy-policy)
• Credits should display a sub screen with license information
  • mikepenz/AboutLibraries seems very promising
  • allows generating list of libraries with license information
  • KMP compliant
  • provide Compose UI for Material 3