fix(player): a library item played from the start keeps its point

A cached file that autoplays from 0:00 fires its one playing event before the resume hook
subscribes, so the hook never counted it as played and reported nothing - not on pause, not on
close. An element already playing when the hook subscribes now counts as played.

frontend/src/lib/resume.dom.test.ts

@@ -94,6 +94,18 @@ describe("useResume", () => {
     expect(save).toHaveBeenLastCalledWith(42, 600, true);
   });
 
+  it("counts an element already playing when it subscribes as played", () => {
+    // A cached file started from 0 autoplays before the effect runs: its one `playing` is gone.
+    const m = fakeMedia();
+    m.metadata();
+    m.play();
+    const save = vi.fn();
+    renderHook(() => useResume(m.el, "7", 0, save));
+    m.at(42);
+    m.pause();
+    expect(save).toHaveBeenLastCalledWith(42, 600, false);
+  });
+
   it("checkpoints while it plays, at most once per interval", () => {
     vi.useFakeTimers();
     const m = fakeMedia();