catalog: replace NullLogger with proper ILogger injection in production DI paths

[CCoupel]

Context

`NullLogger.Instance` is used in `ConfigController` when constructing `SyncService` and `LibraryProvisioner`. This means sync operations produce no logs in production, making debugging difficult for end users.

Problem

`ILoggerFactory` is not registered in Emby's DI container, which prevented injecting it directly into `ConfigController`. As a workaround, `NullLogger.Instance` was used.

Fix

Investigate the correct way to obtain a typed `ILogger` within an Emby plugin controller. Options:

1. Inject `ILogger` and `ILogger` directly (check if registered by Emby)
2. Register these loggers manually in `Plugin.cs` or a service registration hook
3. Use `Plugin.Logger` (base class property) and pass it down

Impact

Without real logging, failures in manual syncs triggered from the UI are silent — users see "0 items failed" with no log entries.

Priority

Medium — Affects debuggability but does not block catalog submission.