`Users`: persistent authentication

[Seerden]

Request

Using redis for session storage and express-session for session cookie functionality, set up persistent authentication.

Implementation

Server

• [x] initialize redis connection
• [x] set up redis session store
• [x] link express app with redis session store
• [x] extend express request type to make typescript happy
• [x] implement log-in functionality
• [x] implement log-in endpoint
• [x] implement log-out endpoint
• [ ] log in on successful registration (follow-up from #1)

Client

• [x] create authentication hook exposing things like login(), logout(), currentUser, isLoggedIn
• [x] create log-in page
• [ ] create log-out component (probably a button for in the sticky navbar (not-yet-implemented)
• [x] locally store client session for UX purposes
  • [x] remove storage value on log-out
  • [x] add storage key on log-in
• [x] reconcile client-side and server-side session state on application mount