[Misc] Simplify type management and DB subscription

[ ] Consider GraphQL, it will be easier to fetch and cache data as needed, subscribe to DB updates, also types will be easier to manage on the frontend
[ ] Since need to add the new routes and all, GraphQL can be handy here. Why GraphQL? The Prisma schema is actually already the GraphQL schema
[ ] Consider tRPC - built for NextJS, easier to manage types and allows subscriptions to updates to DB but rather new technology, but it's less complex to set up than GraphQL
[ ] Instead of having a server running backend, just use NextJS API routes and migrate NextJS to use /app https://www.prisma.io/nextjs
[ ] Server-sent events
[ ] Prisma Pulse is in early access? We wouldn't want to implement our own WebSocket server
[ ] Deploy to Supabase - https://supabase.com/docs/guides/realtime/subscribing-to-database-changes
[ ] Stick to useSWR for now
[ ] handle booking race condition frontend
[ ] make sure you subscribe to/poll for updates to bookings from the backend
[ ] interfaces vs types fix - https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#differences-between-type-aliases-and-interfaces
[ ] State management and data cache-ing and data fetching - see todos in code - https://stackoverflow.com/questions/65364352/is-it-correct-or-good-practice-to-use-swr-together-with-redux - note the diff between UI state and Server Cache-ing State

For sharing types between frontend and backend, there are 2 broad options.

Migrate backend to Next.js and use tRPC

Pros:

Single codebase makes it easier to change things
Allow us to move deployment to Vercel directly, saving on cloud costs
Easier to manage deployments, not having to understand and debug Digital Ocean, Nginx, etc.

Considerations:

Time consuming to migrate the entire backend
Current costs of maintaining the website are not an issue as it is covered by NUSC

Use swagger to annotate the endpoints and generate type definitions that can be used on the client.

Pros:

Simpler to implement - only requires us to add jsdoc annotations to existing endpoints and set up the codegen
An interesting project to work on - more "substance" for team to add to their resume (rather than the typical Next.js webapp)

Cons:

We still have to shift the definitions from backend to frontend, unless we set up a monorepo