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/downloader.py

@@ -4,6 +4,7 @@ Includes fallback support for chat_downloader when VOD-based methods fail.
 """
 
 import os
+import sys
 import subprocess
 import json
 import threading
@@ -45,6 +46,10 @@ class ContentDownloader:
         self.download_live_chat_enabled = config.get('downloadLiveCHAT', True)
         self.use_chat_downloader_primary = config.get('useChatDownloaderPrimary', False)
         self.use_chat_downloader_fallback = config.get('useChatDownloaderFallback', True)
+        default_chat_font = 'Arial' if sys.platform.startswith('win') else 'DejaVu Sans'
+        self.chat_render_font = config.get('chat_render_font', default_chat_font)
+        self.last_chat_render_attempted = False
+        self.last_chat_render_succeeded = False
         
         # Initialize chat_downloader if available
         self.chat_downloader = None
@@ -61,6 +66,11 @@ class ContentDownloader:
         self.chat_thread = None
         self.chat_thread_success = False
         self.chat_thread_error = None
+
+    def reset_chat_render_status(self) -> None:
+        """Reset chat render tracking before a processing pass."""
+        self.last_chat_render_attempted = False
+        self.last_chat_render_succeeded = False
     
     def download_vod(self, vod_info: Dict[str, Any], output_path: str) -> bool:
         """
@@ -190,7 +200,7 @@ class ContentDownloader:
             '-h', '1080',
             '--framerate', '30',
             '--outline',
-            '-f', 'Arial',
+            '-f', self.chat_render_font,
             '--font-size', '22',
             '--update-rate', '1.0',
             '--offline',
@@ -215,6 +225,9 @@ class ContentDownloader:
         
         try:
             print(f'{Fore.YELLOW}Rendering chat video...{Style.RESET_ALL}')
+            print(f'{Fore.CYAN}Using chat font: {self.chat_render_font}{Style.RESET_ALL}')
+            self.last_chat_render_attempted = True
+            self.last_chat_render_succeeded = False
             
             # Build complete command
             full_cmd = [self.twitch_downloader_path, 'chatrender', '-i', json_path, '-o', video_path] + chat_settings
@@ -249,6 +262,7 @@ class ContentDownloader:
                 print(f'{Fore.RED}✗ Chat video file is too small ({file_size} bytes){Style.RESET_ALL}')
                 return False
                 
+            self.last_chat_render_succeeded = True
             print(f'{Fore.GREEN}✓ Chat rendered ({file_size:,} bytes){Style.RESET_ALL}')
             return True