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>

modules/processor.py

@@ -6,7 +6,7 @@ import os
 import subprocess
 from colorama import Fore, Style
 
-from .utils import detect_hardware_acceleration, get_hwaccel_encoder
+from .utils import detect_hardware_acceleration, get_hwaccel_encoder, resolve_hwaccel_type
 
 
 class StreamProcessor:
@@ -36,6 +36,7 @@ class StreamProcessor:
             config.get('ffmpeg_hwaccel', 'auto'), 
             os_type
         )
+        self.hwaccel_type = resolve_hwaccel_type(self.hwaccel_type, os_type)
     
     def process_raw_stream(self, raw_path: str, output_path: str) -> bool:
         """