Add NVIDIA support for FFmpeg in Docker and enhance chat rendering functionality

- Introduced a new docker-compose.nvidia.yml for NVIDIA GPU support.
- Updated dockerstart.bat to allow optional NVIDIA runtime.
- Enhanced ContentDownloader to manage chat rendering status and font settings.
- Improved hardware acceleration detection in utils.py.
- Added tests for hardware acceleration and chat rendering behavior.

Co-authored-by: Copilot <copilot@github.com>

dockerstart.bat

@@ -1,8 +1,15 @@
 @echo off
 setlocal
 
+set NVIDIA_COMPOSE=
+
+if /I "%~1"=="--nvidia" (
+    set NVIDIA_COMPOSE=-f docker-compose.nvidia.yml
+    shift
+)
+
 if "%~1"=="" (
-    echo Usage: .\dockerstart.bat streamer [additional args]
+    echo Usage: .\dockerstart.bat [--nvidia] streamer [additional args]
     exit /b 1
 )
 
@@ -17,4 +24,4 @@ shift
 goto collect_args
 
 :run_compose
-docker compose --env-file .env.development -f docker-compose.yml -f docker-compose.override.yml run --rm twitch-archive python twitch-archive.py -u %STREAMER%%EXTRA_ARGS%
+docker compose --env-file .env.development -f docker-compose.yml -f docker-compose.override.yml %NVIDIA_COMPOSE% run --rm twitch-archive python twitch-archive.py -u %STREAMER%%EXTRA_ARGS%