fix(nav): a linked player, file and search survive what the app does by itself (review round 2)

- Playlists: a link over a playlist the account does not hold plays alone; the rail's own
  fallback no longer counts as a pick that gives the player up.
- The linked opener opens or clears nothing once the address names another player, and stops
  looking (and fetching its row) once it settled.
- Files: a list the server's cap cut — the sorted or searched one too — keeps the link, with a
  notice of its own (EN/HU).
- History: an in-place view rewrite (search refine, count, channel to channel, sub-view)
  drops a reloaded entry's overlay marks (replaceView); a landing on a channel opened from a
  search keeps the search; the Feed press on a search opens the plain feed.
- Files/Playlists: an emptied search is written at once.
- Client log: plf/cf (column text filters) are typed keys; the shell has none of its own.
- Contract: writers outside lib/ take a literal or a lib/ function's result; every URL key is
  sorted typed or not; the writer regexes are held by a fixture; sub-views named; the bookmark
  net reads page tags.
- Feed defaults in one constant; one live-search queue helper; Scheduler writes through the
  Activity codec; notRun copy (EN/HU) names Forward and a plain "Search YouTube" button.

frontend/src/lib/api.ts

@@ -20,7 +20,7 @@ import { setupApi } from "./api/setup";
 export type * from "./api/setup";
 import { feedApi } from "./api/feed";
 export type * from "./api/feed";
-export { TAKEOUT_JOB } from "./api/feed";
+export { FEED_DEFAULT_SHOW, FEED_DEFAULT_SORT, TAKEOUT_JOB } from "./api/feed";
 import { discoverApi } from "./api/discover";
 export type * from "./api/discover";
 export { DISCOVER_BUDGETS, HERO_TIERS, discoverCardKey } from "./api/discover";