feat(app,android): play from the Downloads page, and say why a download waits

- A finished download on the desktop could only be deleted from the
  Downloads page; watching it meant finding it in the library. Finished
  rows gain Play, from wherever the library says it was left, and Open.
- Android showed "Queued" for a download WorkManager was holding back
  on mobile data because of Wi-Fi only, or for want of any connection,
  which reads as stuck. Those now say "Waiting for Wi-Fi" and "Waiting
  for a connection".

crates/pstr-app/src/app.rs

@@ -112,6 +112,9 @@ const NAV: [Page; 5] = [
 pub enum Action {
     Goto(Page),
     Play(PlaybackTarget),
+    /// Play a file from wherever the library says it was left, for a caller
+    /// whose target may be older than that — a download queued last week.
+    PlayResuming(PlaybackTarget),
     /// Download one or more files as complete local copies.
     MakeOffline(Vec<PlaybackTarget>),
     PauseDownload(DownloadKey),
@@ -1559,6 +1562,18 @@ impl App {
                 self.form.repair_password.clear();
                 self.engine.repair_share(id, url, password);
             }
+            Action::PlayResuming(mut target) => {
+                target.resume_at = self.library.titles.iter().find_map(|title| {
+                    title
+                        .episodes()
+                        .find(|episode| {
+                            episode.node.share_id == target.share_id
+                                && episode.node.link_id == target.link_id
+                        })
+                        .and_then(|episode| episode.resume_at())
+                });
+                self.apply(ctx, Action::Play(target));
+            }
             Action::OpenShareForm => {
                 self.page = Page::Shares;
                 self.form.focus = true;

crates/pstr-app/src/ui/downloads.rs

@@ -1,6 +1,6 @@
 //! Inspectable desktop download queue.
 
-use crate::app::Action;
+use crate::app::{Action, Page};
 use crate::engine::{DownloadItem, DownloadState};
 use crate::{theme, ui};
 
@@ -222,6 +222,14 @@ fn buttons(ui: &mut egui::Ui, item: &DownloadItem, actions: &mut Vec<Action>) {
             }
         }
         DownloadState::Completed => {
+            // The point of a download is to watch it, and the library is a
+            // detour from here — offline most of all.
+            if ui::accent_button(ui, "Play").clicked() {
+                actions.push(Action::PlayResuming(item.target.clone()));
+            }
+            if ui.button("Open").on_hover_text("Go to its title").clicked() {
+                actions.push(Action::Goto(Page::Title(item.target.title_key.clone())));
+            }
             if ui
                 .button("Delete")
                 .on_hover_text("Delete the offline copy; keep the online source")