feat: polish prompt ux and fix z hiding sources without seeder data

- new PromptHints action row shared by the folder and trackers prompts
- download-to prompt shows the torrent name and size, enter reads "download"
- export torrent rebound from T to s and centralized in the store
- footer trimmed to essentials, d/D and z detail live in the ? sheet
- z keeps FitGirl and SubsPlease rows: their feeds carry no seeder data,
  a new per-source reportsHealth flag marks seeders: 0 as unknown, not dead
- version 1.3.0

scripts/render-previews-impl.tsx

@@ -100,6 +100,7 @@ function makeStore(
     requestDownloadTo: noop,
     copyMagnet: noop,
     openDownloadFolder: noop,
+    exportTorrent: noop,
     notice: null,
     setNotice: noop,
     quitAll: noop,