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/src/components/DownloadIntake.dom.test.tsx

@@ -24,6 +24,7 @@ import DownloadIntake from "./DownloadIntake";
 import { LinkBox } from "./LinkBox";
 import { clearPendingDownload, requestLinkBox } from "../lib/downloadIntake";
 import { ensureNavId } from "../lib/history";
+import { pushLayer, removeLayer } from "../lib/layerStack";
 
 afterEach(() => {
   cleanup();
@@ -79,6 +80,18 @@ describe("DownloadIntake · a pasted link", () => {
     expect(dialog()).toBeNull();
   });
 
+  it("with a player or a menu on top (a layer, no aria-modal), a paste is not a download", async () => {
+    render(<DownloadIntake />);
+    const layer = pushLayer();
+    try {
+      paste(document.body, "https://a.example/1");
+      await act(async () => {});
+      expect(dialog()).toBeNull();
+    } finally {
+      removeLayer(layer);
+    }
+  });
+
   it("closing the dialog closes it", async () => {
     render(<DownloadIntake />);
     paste(document.body, "https://a.example/1");
@@ -102,6 +115,20 @@ describe("LinkBox", () => {
     expect((field as HTMLInputElement).value).toBe("");
   });
 
+  it("a clipboard link read on focus never replaces what was typed while it was read", async () => {
+    let answer: (text: string) => void = () => {};
+    Object.defineProperty(navigator, "clipboard", {
+      configurable: true,
+      value: { readText: () => new Promise<string>((resolve) => (answer = resolve)) },
+    });
+    render(<LinkBox />);
+    const box = screen.getByRole("textbox");
+    fireEvent.focus(box);
+    fireEvent.change(box, { target: { value: "https://typed.example/1" } });
+    await act(async () => answer("https://clipboard.example/2"));
+    expect((box as HTMLInputElement).value).toBe("https://typed.example/1");
+  });
+
   it("an empty box downloads nothing", async () => {
     render(
       <>