feat: add admin login page and authentication API

- Created a new login page for admin access at frontend/admin/login/index.html.
- Implemented form submission with error handling for login credentials.
- Updated frontend/index.html to mute the video player and removed unnecessary Alpine.js data binding.
- Enhanced manifest URL resolution in frontend/src/main.ts to include cache-busting parameters.
- Modified vite.config.ts to include the new admin login page in the build process.
- Updated nginx.conf to handle admin login routing, authentication, and API proxying for admin actions.

backend/playout/start-playout.sh

@@ -26,17 +26,27 @@ fi
 
 echo "Playlist validated successfully. Starting continuous HLS playout..."
 
+mkdir -p /app/hls
+rm -f /app/hls/playlist.m3u8 /app/hls/init.mp4 /app/hls/segment_*.ts /app/hls/segment_*.m4s
+
 # Run FFmpeg in a loop for continuous playback
 while true; do
-  echo "[$(date)] Starting FFmpeg playout with -c copy (stream copy mode)..."
+  echo "[$(date)] Starting FFmpeg playout with browser-safe HLS encoding..."
   ffmpeg -re -f concat -safe 0 -i "$PLAYLIST_PATH" \
-    -c:v copy -c:a copy \
+    -map 0:v:0 -map 0:a:0? \
+    -vf "scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,fps=30,format=yuv420p" \
+    -c:v libx264 -preset veryfast -pix_fmt yuv420p \
+    -profile:v high -level 4.0 \
+    -r 30 -g 60 -keyint_min 60 -sc_threshold 0 \
+    -c:a aac -ar 48000 -ac 2 -b:a 128k \
     -f hls \
     -hls_time "${HLS_SEGMENT_DURATION}" \
     -hls_list_size "${HLS_WINDOW_SIZE}" \
+    -hls_segment_type fmp4 \
+    -hls_fmp4_init_filename init.mp4 \
     -strftime 1 \
-    -hls_flags delete_segments+append_list \
-    -hls_segment_filename "/app/hls/segment_%Y%m%d_%H%M%S.ts" \
+    -hls_flags delete_segments+independent_segments \
+    -hls_segment_filename "/app/hls/segment_%Y%m%d_%H%M%S.m4s" \
     "/app/hls/playlist.m3u8" || echo "FFmpeg exited with error (will restart in 5s per ADR-001 resilience requirements)..."
 
   echo "Playout loop crashed or ended. Restarting in 5 seconds..."