Resume a figure after a library rescan

play_figure resumed only when the player's playlist *was* the figure's playlist
object. rescan_library rebuilds every Playlist, so after the refresh button - or
the podcast poller landing a new episode, every few hours on its own - putting a
figure back started it over. Playlist is a frozen dataclass: compare by value.

The album picker's "keep what is already playing" check had the same identity
comparison and restarted the album after a rescan; it compares by value too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

python-backend/tests/test_reactions.py

@@ -126,6 +126,22 @@ async def test_putting_the_same_figure_back_resumes_where_it_left_off(
     mouse.check("track", "1")
 
 
+async def test_resuming_survives_a_library_rescan(
+    mouse: SimulatorDriver, sim: Simulation
+) -> None:
+    """A rescan rebuilds every Playlist object; resuming must not depend on identity."""
+    await mouse.place("fuchs")
+    await mouse.wait(TRACK_SECONDS + 1)
+    mouse.check("track", "1")
+
+    await mouse.remove()
+    await sim.app.rescan_library()
+    await mouse.place("fuchs")
+
+    mouse.check("playing", "true")
+    mouse.check("track", "1")
+
+
 async def test_a_different_figure_starts_from_the_top(mouse: SimulatorDriver) -> None:
     await mouse.place("fuchs")
     await mouse.wait(TRACK_SECONDS + 1)