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/TranscodeSession.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 
 namespace MediaBrowser.Controller.MediaEncoding;
 
@@ -46,4 +47,40 @@ public sealed class TranscodeSession
     /// Gets or sets the last durable playback offset in ticks, used to resume playback after failover.
     /// </summary>
     public long LastDurablePlaybackOffset { get; set; }
+
+    /// <summary>
+    /// Creates a session record for an HLS output, deriving <see cref="ManifestPath"/> and
+    /// <see cref="SegmentPathPrefix"/> from the playlist path so that cleanup can recognise
+    /// every file the session owns.
+    /// </summary>
+    /// <param name="playSessionId">The play session identifier.</param>
+    /// <param name="mediaSourceId">The media source identifier.</param>
+    /// <param name="ownerPod">The name of the pod that owns the session.</param>
+    /// <param name="playlistPath">The absolute path of the HLS playlist (.m3u8) file.</param>
+    /// <param name="leaseDuration">The initial lease duration.</param>
+    /// <returns>The new <see cref="TranscodeSession"/>.</returns>
+    public static TranscodeSession CreateForPlaylist(
+        string playSessionId,
+        string mediaSourceId,
+        string ownerPod,
+        string playlistPath,
+        TimeSpan leaseDuration)
+        => new TranscodeSession
+        {
+            PlaySessionId = playSessionId,
+            OwnerPod = ownerPod,
+            LeaseExpiresUtc = DateTime.UtcNow.Add(leaseDuration),
+            ManifestPath = playlistPath,
+            SegmentPathPrefix = GetSegmentPathPrefix(playlistPath),
+            MediaSourceId = mediaSourceId,
+        };
+
+    /// <summary>
+    /// Gets the prefix every segment file of the HLS output at <paramref name="playlistPath"/> starts with.
+    /// Segments are written as <c>&lt;playlist path without extension&gt;&lt;index&gt;&lt;segment extension&gt;</c>.
+    /// </summary>
+    /// <param name="playlistPath">The absolute path of the HLS playlist (.m3u8) file.</param>
+    /// <returns>The segment path prefix.</returns>
+    public static string GetSegmentPathPrefix(string playlistPath)
+        => Path.ChangeExtension(playlistPath, null) ?? playlistPath;
 }