Holds the feed tab the index opens on until a user picks one. The tabs
themselves are FEED_TABS in shared/paths.ts, since they are path
segments the server reserves at the root.
v
DEFAULT_FEED_TAB: FeedTab
The tab the bare / and /<category> show visitors, and users who haven't
picked one in their settings.
Usage
import * as mod from "src/config/feedTabs.ts";