fix(reader): the Takeout import holds up under abuse, races and a run it cannot see

- Uploads: one at a time per user and ten an hour, each refused only after its body arrived;
  the history read an entry at a time (32 MiB cap), a Watch later list capped at YouTube's 5000,
  a user's kept videos at 200k; any unreadable shape is a 422, not a 500.
- Quota: Watch later lookups stop at the backfill reserve and at a per-user daily share; what is
  not asked about waits, known videos still go in, and the shorts job retries the rest.
- Staging and settling share one per-user advisory lock (no deadlock); a run settles only the
  rows it read, so a row staged meanwhile is never called gone.
- A failed run's notice names a translated failure, never the upstream's text.
- The status says when an import is queued; the page watches it to its end even when left, then
  reads the feed, its counts and the playlists again.
- Settings: one live region, the zone kept (unavailable) while a run goes, focus handed back,
  a missed drop kept from the browser, an oversize file refused before it is sent.
- Scheduler and run lists show Takeout runs by the importing user.

frontend/src/lib/api/feed.ts

@@ -164,12 +164,26 @@ export interface TakeoutUpload {
   other: number;
   malformed: number;
 }
-export type TakeoutKind = "watched" | "watch_later";
-// A kept video's outcome (`reader.models.TakeoutOutcome`), or "waiting" while the catalog does not
-// know it yet: watched / kept (the user's own state here stood) / short for the history; added /
-// present / missing for Watch later.
-export type TakeoutCounts = Partial<Record<string, number>>;
+// The two files (`reader.models.TakeoutKind`) and a kept video's outcome (`TakeoutOutcome`): watched
+// / kept (the user's own state here stood) / short for the history; added / present / missing for
+// Watch later. backendIds.contract.test holds both lists to the backend's enums.
+export const TAKEOUT_KINDS = ["watched", "watch_later"] as const;
+export const TAKEOUT_OUTCOMES = [
+  "watched",
+  "kept",
+  "short",
+  "added",
+  "present",
+  "missing",
+] as const;
+export type TakeoutKind = (typeof TAKEOUT_KINDS)[number];
+// Each outcome's count, and "waiting" for the videos the import could not settle yet.
+export type TakeoutCounts = Partial<Record<(typeof TAKEOUT_OUTCOMES)[number] | "waiting", number>>;
 export interface TakeoutStatus {
+  /** An import is queued and its run not started: `run` is still the one before it. */
+  queued: boolean;
+  /** The largest file the upload takes. */
+  max_bytes: number;
   run: {
     status: RunStatus;
     started_at: string | null;