fix(worker): run streamrip on one persistent event loop (fixes Qobuz download failures)

Each search/download called asyncio.run, creating and closing a fresh event loop.
streamrip's module-global download-concurrency Semaphore binds to the loop on first
use, so the 2nd+ download reused a Semaphore bound to a closed loop -> "Semaphore is
bound to a different event loop", tracks failed, album arrived short -> "incomplete
download" / needs_attention. Run all streamrip coroutines on one persistent loop.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

worker/tests/test_streamrip_loop.py

@@ -0,0 +1,17 @@
+import asyncio
+
+from lyra_worker.adapters._streamrip import _run
+
+
+def test_run_reuses_one_persistent_loop_across_calls():
+    # The event-loop fix: unlike asyncio.run (which creates AND closes a fresh loop per call),
+    # _run runs every streamrip coroutine on ONE persistent loop — so streamrip's loop-bound
+    # global Semaphore stays valid across downloads instead of orphaning on a closed loop.
+    async def current_loop():
+        return asyncio.get_running_loop()
+
+    loop_a = _run(current_loop())
+    loop_b = _run(current_loop())
+
+    assert loop_a is loop_b            # same loop reused, not a fresh one each call
+    assert not loop_a.is_closed()      # still open (asyncio.run would have closed it)