chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

shared/constants.ts

@@ -0,0 +1,5 @@
+export const USER_PRESENCE_INTERVAL = 5000;
+
+export const MAX_AVATAR_DISPLAY = 6;
+
+export const MAX_TITLE_LENGTH = 100;