refactor: replace refresh & access token with auth token only

changes authentication to no longer use a refresh token & access token
for accessing protected endpoints. Instead only an auth token is used.

Before the login flow was:

Login -> get refresh (stored as HttpOnly cookie) + access token (stored in memory) ->
  protected endpoint request (attach access token as Authorization header) -> access token expires in
  15 minutes, so use refresh token to obtain new one when that happens

now it looks like this:

Login -> get auth token (stored as HttpOnly cookie) -> make protected endpont
request (token sent)

the reasoning for using the refresh + access token was to reduce DB
calls, but in the end I don't think its worth the hassle.

internal/db/query/token.sql

@@ -1,14 +1,14 @@
--- name: GetRefreshTokenByID :one
-SELECT * FROM refresh_token WHERE token_id = $1;
+-- name: GetAuthTokenByID :one
+SELECT * FROM auth_token WHERE token_id = $1;
 
--- name: CreateRefreshToken :one
-INSERT INTO refresh_token (user_id, created_at, expires_at) VALUES ($1, $2, $3) RETURNING *;
+-- name: CreateAuthToken :one
+INSERT INTO auth_token (user_id, created_at, expires_at) VALUES ($1, $2, $3) RETURNING *;
 
--- name: DeleteRefreshTokenByID :exec
-DELETE FROM refresh_token WHERE token_id = $1;
+-- name: DeleteAuthTokenByID :exec
+DELETE FROM auth_token WHERE token_id = $1;
 
--- name: DeleteRefreshTokenByUserID :exec
-DELETE FROM refresh_token WHERE user_id = $1;
+-- name: DeleteAuthTokenByUserID :exec
+DELETE FROM auth_token WHERE user_id = $1;
 
 -- name: DeleteExpiredTokens :exec
-DELETE FROM refresh_token WHERE expires_at <= NOW();
+DELETE FROM auth_token WHERE expires_at <= NOW();