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

MediaBrowser.Controller/MediaEncoding/NullTranscodeSessionStore.cs

@@ -24,8 +24,8 @@ public sealed class NullTranscodeSessionStore : ITranscodeSessionStore
         => Task.CompletedTask;
 
     /// <inheritdoc />
-    public Task RenewLeaseAsync(string playSessionId, CancellationToken cancellationToken = default)
-        => Task.CompletedTask;
+    public Task<bool> RenewLeaseAsync(string playSessionId, string ownerPod, CancellationToken cancellationToken = default)
+        => Task.FromResult(true);
 
     /// <inheritdoc />
     public Task DeleteAsync(string playSessionId, CancellationToken cancellationToken = default)
@@ -34,16 +34,4 @@ public sealed class NullTranscodeSessionStore : ITranscodeSessionStore
     /// <inheritdoc />
     public Task<IEnumerable<TranscodeSession>> GetActiveSessionsAsync(CancellationToken cancellationToken = default)
         => Task.FromResult<IEnumerable<TranscodeSession>>(Array.Empty<TranscodeSession>());
-
-    /// <inheritdoc />
-    public Task SetLiveStreamAsync(LiveStreamSession session, CancellationToken cancellationToken = default)
-        => Task.CompletedTask;
-
-    /// <inheritdoc />
-    public Task<LiveStreamSession?> TryGetLiveStreamAsync(string liveStreamId, string sessionIdOrPlaySessionId, CancellationToken cancellationToken = default)
-        => Task.FromResult<LiveStreamSession?>(null);
-
-    /// <inheritdoc />
-    public Task DeleteLiveStreamAsync(string liveStreamId, string sessionIdOrPlaySessionId, CancellationToken cancellationToken = default)
-        => Task.CompletedTask;
 }