fix: make transcode leases ownership-checked and cleanup-aware

Cleanup never matched a live session because the controller registered empty
manifest and segment paths, renewal was a read-modify-write that could revert a
takeover, and the takeover script compared an ISO date to a number, so it errored.

- populate the session record's manifest and segment paths from the playlist path
- renew the lease via a Lua compare-and-set on the owning pod
- store the lease expiry as unix milliseconds so the scripts can compare it
- retain the session record past its lease so an orphan can still be taken over
- test the Redis store against a real Redis, including the renew-vs-takeover race
- drop the live stream record nothing ever read back

tests/Jellyfin.MediaEncoding.Tests/Transcoding/InMemoryTranscodeSessionStoreTests.cs

@@ -7,12 +7,12 @@ using Xunit;
 namespace Jellyfin.MediaEncoding.Tests.Transcoding;
 
 /// <summary>
-/// Unit tests for the HA session-store contract: lease expiry, double-claim prevention,
-/// heartbeat renewal, and stale-session cleanup.
-/// All tests exercise <see cref="InMemoryTranscodeSessionStore"/> which implements the
-/// <see cref="ITranscodeSessionStore"/> interface that will be backed by Redis in Phase 5.2.
+/// Unit tests for the <see cref="ITranscodeSessionStore"/> contract — lease expiry, double-claim
+/// prevention, ownership-checked renewal and stale-session cleanup — against
+/// <see cref="InMemoryTranscodeSessionStore"/>, the reference implementation. The Redis-backed
+/// implementation is covered by <c>RedisTranscodeSessionStoreTests</c> against a real Redis.
 /// </summary>
-public class TranscodeManagerTests
+public class InMemoryTranscodeSessionStoreTests
 {
     private static TranscodeSession CreateSession(
         string id,
@@ -123,7 +123,7 @@ public class TranscodeManagerTests
         var session = CreateSession("session-renew", "pod-a", originalExpiry, lastSegmentIndex: 2, lastOffset: 10_000_000L);
         await store.SetAsync(session, TestContext.Current.CancellationToken);
 
-        await store.RenewLeaseAsync("session-renew", TestContext.Current.CancellationToken);
+        Assert.True(await store.RenewLeaseAsync("session-renew", "pod-a", TestContext.Current.CancellationToken));
 
         var renewed = await store.TryGetAsync("session-renew", TestContext.Current.CancellationToken);
         Assert.NotNull(renewed);
@@ -132,6 +132,25 @@ public class TranscodeManagerTests
             "Renewed lease expiry should be later than the original expiry.");
     }
 
+    /// <summary>
+    /// A renewal from a pod that no longer owns the lease must fail and must not revert ownership.
+    /// </summary>
+    [Fact]
+    [Trait("Category", "UnitTest")]
+    public async Task RenewLeaseAsync_ByNonOwner_ReturnsFalse()
+    {
+        var store = new InMemoryTranscodeSessionStore();
+        var session = CreateSession("session-renew-other", "pod-a", DateTime.UtcNow.AddMilliseconds(-1));
+        await store.SetAsync(session, TestContext.Current.CancellationToken);
+
+        Assert.True(await store.TryTakeoverAsync("session-renew-other", "pod-b", TestContext.Current.CancellationToken));
+        Assert.False(await store.RenewLeaseAsync("session-renew-other", "pod-a", TestContext.Current.CancellationToken));
+
+        var current = await store.TryGetAsync("session-renew-other", TestContext.Current.CancellationToken);
+        Assert.NotNull(current);
+        Assert.Equal("pod-b", current.OwnerPod);
+    }
+
     /// <summary>
     /// Stale-session cleanup: an expired session can be deleted without error, and a
     /// subsequent <see cref="ITranscodeSessionStore.TryGetAsync"/> returns <c>null</c>.