fix(player): stop AbortError storm from HLS stall recovery (DR-096)

Html5PlayerAdapter.play() reported every interrupted play attempt as a
player error. While an HLS stream stalls, hls.js' gap-controller nudges
the element to recover, which cancels the pending play() promise and
raises AbortError ("play() request was interrupted by a call to
pause()"). That is transient — the element is still trying to play — but
it hit host.onError roughly once a second for the whole stall, leaving
the UI stuck reporting paused.

Treat an interrupted play as a debug-level non-event, and memoise the
in-flight attempt so the UI and recovery paths share one element.play()
rather than stacking calls that abort each other.

This is the loop amplifier, complementing DR-095 which removed the
dead-segment stall that triggered it.

Note: webviewAudioAdapter.play() has the same raw shape but is not
implicated — audio playback does not go through hls.js — so it is left
unchanged rather than widening this fix.

src/lib/player/adapters/html5Adapter.test.ts

@@ -95,6 +95,63 @@ describe("Html5PlayerAdapter", () => {
     expect(video.play).toHaveBeenCalledTimes(1);
   });
 
+  // A stalling HLS stream makes hls.js' gap-controller nudge the element, which
+  // aborts an in-flight play(). That AbortError is transient — the element is
+  // still trying to play — so it must not be surfaced as a player error, or the
+  // UI reports failure ~once a second for the whole stall.
+  it("play() does not report an interrupted-by-pause AbortError as an error", async () => {
+    const abort = new DOMException(
+      "The play() request was interrupted by a call to pause().",
+      "AbortError"
+    );
+    video.play = vi.fn(async () => {
+      throw abort;
+    });
+
+    await adapter.play();
+
+    expect(host.onError).not.toHaveBeenCalled();
+  });
+
+  it("play() still reports a genuine failure", async () => {
+    video.play = vi.fn(async () => {
+      throw new DOMException("no supported source", "NotSupportedError");
+    });
+
+    await adapter.play();
+
+    expect(host.onError).toHaveBeenCalledTimes(1);
+    expect(String((host.onError as any).mock.calls[0][0])).toContain("play() failed");
+  });
+
+  it("play() coalesces concurrent attempts into one element.play() call", async () => {
+    // During a stall the UI and recovery paths can both ask to play. Stacking
+    // element.play() calls is what generates the AbortError storm.
+    let resolvePlay: () => void = () => {};
+    video.play = vi.fn(
+      () =>
+        new Promise<void>((r) => {
+          resolvePlay = () => {
+            video.paused = false;
+            r();
+          };
+        })
+    );
+
+    const first = adapter.play();
+    const second = adapter.play();
+    resolvePlay();
+    await Promise.all([first, second]);
+
+    expect(video.play).toHaveBeenCalledTimes(1);
+  });
+
+  it("play() works again after a previous attempt settled", async () => {
+    await adapter.play();
+    await adapter.play();
+    expect(video.play).toHaveBeenCalledTimes(2);
+  });
+
   it("pause() calls element.pause()", async () => {
     video.paused = false;
     await adapter.pause();