feat(files): download from anywhere — a link box, a pasted link, the palette; the running downloads in a tray

- Files toolbar link box (paste button, Enter); a lone http(s) link pasted onto any page opens the one
  app-wide download dialog, which now names the link; the palette's "Download from a link…" focuses
  the box on its history entry.
- The download tray, bottom right on every page: what waits, runs, is paused or failed (reason +
  Retry, the queue's right-click / "…" menu), and what finished in this tab as "Done · Open" until
  closed; folds to a pill (per-account pref); closed, it stays shut — across a reload — until the
  work changes or something finishes. Back to top steps up over it, the page end keeps clear.
- A finish is announced once: "Downloaded: …", whether a phone plays it, Copy link + Open (toasts
  and notices may carry a second action).
- The inbox's ready notice opens the file in its folder: download_done carries job_id + folder_id.
- GET /api/downloads is the queue only (in flight, failed, finished in the last 10 minutes), with
  each row's source key.

frontend/src/components/AppCommandPalette.tsx

@@ -1,7 +1,17 @@
 import { useMemo } from "react";
 import { useTranslation } from "react-i18next";
 import { useQuery } from "@tanstack/react-query";
-import { Bug, Flag, Keyboard, ListVideo, Palette, Sparkles, Square, Tv } from "lucide-react";
+import {
+  Bug,
+  Download,
+  Flag,
+  Keyboard,
+  ListVideo,
+  Palette,
+  Sparkles,
+  Square,
+  Tv,
+} from "lucide-react";
 import CommandPalette, { type CommandGroup } from "./ui/CommandPalette";
 import { api } from "../lib/api";
 import { qk } from "../lib/queryKeys";
@@ -10,6 +20,7 @@ import { moduleDef, moduleOrder } from "../lib/modules";
 import { SCHEMES, type Scheme } from "../lib/theme";
 import { closePalette, toggleKeyboardHelp, usePaletteOpen } from "../lib/keymap";
 import { requestSurprise } from "../lib/homeIntent";
+import { requestLinkBox } from "../lib/downloadIntake";
 import { openRecorderStart } from "../lib/debugRecorder";
 import { useDebugRecording } from "./useDebugRecording";
 import { useNavigationActions } from "./navigationContext";
@@ -145,6 +156,14 @@ export default function AppCommandPalette() {
           // polcodról" under a command that promised a surprise (owner's call, 2026-09-19).
           run: () => setPage("home", requestSurprise),
         },
+        // Downloading is an action you start anywhere; with nothing pasted yet, the place to paste is
+        // the Files page's link box (lib/downloadIntake), focused on arrival.
+        {
+          id: "action:downloadLink",
+          label: t("palette.actions.downloadLink"),
+          icon: <Download className="w-4 h-4" />,
+          run: () => setPage("files", requestLinkBox),
+        },
         {
           id: "action:shortcuts",
           label: t("keys.title"),