android: the downloads say so in the shade

A Save still running with the app in the background now posts a progress
notice — how many files, the one it is on, a bar, Stop all and Open — and
takes it down when the queue empties. It sits on its own low-importance
channel so it can be silenced without silencing the player's card, and
rides its own dataSync foreground service rather than the media one: a
mediaPlayback service stops itself when the bar empties, a download is not
playback, and nothing else was keeping the process alive for a Save with
nothing playing — which is how the first real Save died, four tracks in.
Stop all goes through the same cancel(id) a row's tap takes, and Transfers
grew the matching button beside Clear finished. The walk pushes two rows
straight into the transfer store and reads the real notification back out
of `dumpsys notification`, without fetching anything.

src/lib/mockLibrary.js

@@ -635,6 +635,11 @@ function mockCatalog(cmd, args) {
     if (cmd === "plugin:storage|all_files_access") return Promise.resolve({ granted: true });
     if (cmd === "plugin:storage|request_all_files_access") return Promise.resolve();
     if (cmd === "plugin:storage|pick_image") return Promise.resolve({ path: "C:\\mock\\photo.jpg" });
+    /* the downloads notice: the mock walk cannot see the shade, so the calls
+       are simply answered — what the walk reads is __ss.xfn, the app's own
+       record of having posted and cleared */
+    if (cmd === "plugin:transfer-notice|update") return Promise.resolve();
+    if (cmd === "plugin:transfer-notice|clear") return Promise.resolve();
     if (cmd === "plugin:share|pending_share") {
         /* the harness shares by setting window.__ssMock.share and waking the page */
         const t = (typeof window !== "undefined" && window.__ssMock?.share) || null;