Fix ridiculous regex-trie of all usernames

[danneu]

One of the most hilarious parts of the guild's code is that on server boot it loads every single username into the database into a regex so that the application can scan for valid mentions in posts/pms.

I quick hack would be to at least filter out inactive users.

[danneu]

guild/server/db/index.ts

Line 2145 in e06cc40

export async function findAllUnames() {

found a fn findAllUnamesJson that does this but now findAllUnames just loads unames for users who have at least not been nuked and have logged in within a year 🤣

[danneu]

i started to fix this in #225 where i load a user of filtered ("active") usernames on server boot (it's only 3000-4000 unames).

i figured i could also just modify the cached set in the register-user and nuke-user route. but that only updates the cache for a single machine in the cluster so it's a no-go.

instead i would have to set up pgnotify so every machine can subscribe to new user / nuked user pg events. that way they would only have to load the set once and then keep it up to date instead of increasing cache interval.

not sure it's worth it though. but the problem with a stale cache is that you can't [@mention] someone whose uname isn't in the cache.