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/e2e/global.setup.ts

@@ -1,9 +1,9 @@
 import { test as setup, expect, type Page } from "@playwright/test";
 import { execFileSync } from "node:child_process";
-import { mkdirSync, readFileSync } from "node:fs";
+import { mkdirSync, readFileSync, writeFileSync } from "node:fs";
 import { dirname, resolve } from "node:path";
 import { fileURLToPath } from "node:url";
-import { MEMBER_STORAGE } from "./helpers";
+import { MEMBER_STORAGE, SEED_FILE } from "./helpers";
 import { retryConnect } from "./retryConnect";
 
 /**
@@ -99,6 +99,8 @@ setup("seed + authenticate", async ({ page, browser }) => {
         { input: readFileSync(SEED_SCRIPT) },
       );
       console.log(`[e2e seed] ${out.toString().trim()}`);
+      // What the seed chose, for the specs that need one of its videos (helpers.seeded).
+      writeFileSync(SEED_FILE, out);
     } catch (err: unknown) {
       const e = err as { stderr?: Buffer; message?: string };
       throw new Error(`E2E seed failed: ${e.stderr?.toString() || e.message}`);