fix(files): review round 1, the page — honest states, the keyboard, the tray's words

- A library past the list's cap is searched and sorted on the server; the count says "the newest".
- Each folder and each search opens on its first page (DataTable pageScope, useCardPager scope).
- A file dropped where the page takes none never reaches the browser (which would unload the app).
- The viewer's arrows wait while a layer opened from it is on top, and scroll a wide text line;
  a text shows its first 5000 lines and says where the rest is.
- Confirms name the file (no more "your downloads"); the asking menu rows end in "…".
- The tray names a running step beside its bar, shows a pause mark for paused work, polls slowly
  while only paused work waits, and forgets a finished file that was deleted.
- An unchanged rename sends nothing; a paste opens the download dialog only with nothing on top;
  the link box never replaces what was typed.
- Honest states: folders that failed to load, a file no longer there, the storage figure; the rail
  says "nothing downloaded" only when there is nothing.
- Focus after deleting the open folder and when the format form opens; the format name's label.
- ui/Meter (one danger line for both quota bars) and ui/RenameField in the platform layer.
- Copy fixes, stale comments and the speculative hub key; a contract test for the list's
  parameters; e2e: the Files page and the paste intake.

frontend/e2e/nav.spec.ts

@@ -10,7 +10,7 @@ test.describe("page switching", () => {
   // `nav-admin`) that opens a panel of them — the spec still listed them as rail rows of their own,
   // and it failed on every run for a while without anyone seeing it, because e2e was in no
   // required gate (it is now part of `release`).
-  const RAIL = ["channels", "playlists", "stats", "settings", "feed"];
+  const RAIL = ["channels", "playlists", "files", "stats", "settings", "feed"];
   const ADMIN = ["scheduler", "config", "users", "audit"];
 
   test("each rail item activates its page", async ({ page }) => {