merge: resolve CoreAppHost conflict with main, drop dead redisConnectionString local

docs/FORK-DIFF.md

@@ -37,6 +37,9 @@ auth or plugin logic is rewritten.
 | `MediaBrowser.Controller/MediaEncoding/TranscodeStoreOptions.cs` | `RedisConnectionString`, `LeaseDurationSeconds` and `SessionRetentionSeconds` |
 | `MediaBrowser.Controller/MediaEncoding/NullTranscodeSessionStore.cs` | No-op store used when no Redis connection is configured |
 | `Emby.Server.Implementations/MediaEncoding/RedisTranscodeSessionStore.cs` | Redis store; sessions under `jellyfin:transcode:{playSessionId}`, key TTL is the retention window so an orphaned session outlives its lease |
+| `Emby.Server.Implementations/MediaEncoding/TranscodeStoreConnectivityProbe.cs` | Startup ping; an unreachable configured store is logged at `Error` instead of failing open silently |
+| `Jellyfin.Server/Extensions/TranscodeStoreServiceCollectionExtensions.cs` | Store selection, logged at `Information` so the active store is visible at startup |
+| `Jellyfin.Server/Extensions/ConfigurationBuilderExtensions.cs` | Reads bare `Jellyfin__*` environment variables into the `Jellyfin:*` configuration root |
 
 Lease takeover and renewal each run as a single Lua script, so concurrent pods cannot both
 claim an expired lease and a renewal cannot revert a takeover. The expiry is stored as unix