docs(viewer): Document splash screen options and auto-reconnect

Adds documentation for new features related to the viewer mode in `README.md`:
- Details `--splashscreen-idle` and `--splashscreen-connecting` CLI options for custom splash images.
- Explains that `publish.py --view` now keeps HDMI output active during publisher disconnections, displaying the idle splash screen instead of a black frame.
- Notes the automatic re-requesting of streams by the viewer after graceful disconnects.
- Updates the 'Recent Changes' section to reflect these enhancements from January 2025.

[auto-enhanced]

Author: steveseguin

README.md

@@ -356,6 +356,10 @@ options:
   --pipeline PIPELINE   A full custom pipeline
   --record RECORD       Specify a stream ID to record to disk. System will not publish a stream when enabled.
   --view VIEW           Specify a stream ID to play out to the local display/audio.
+  --splashscreen-idle PATH
+                        Provide a still image that is shown whenever the remote video is muted or disconnected (viewer mode).
+  --splashscreen-connecting PATH
+                        Optional splash image displayed while the viewer is waiting for the remote stream to start.
   --save                Save a copy of the outbound stream to disk. Publish Live + Store the video.
   --record-room         Record all streams in a room to separate files. Requires --room parameter. 
                         Audio recording is enabled by default; use --noaudio to disable.
@@ -389,6 +393,13 @@ options:
   --clockstamp          Add a clock overlay to the video output, if possible
 ```
 
+##### Viewer splash screens & auto-restart
+
+- Running `python3 publish.py --view <stream-id>` now keeps the HDMI output alive while waiting for the publisher to reconnect. The idle splash stays visible instead of dropping to black.
+- Use `--splashscreen-idle /path/to/image.jpg` to provide a 16:9 still that is shown whenever the remote video is muted or hangs up. If not supplied the viewer falls back to a built-in blank frame.
+- Optionally supply `--splashscreen-connecting /path/to/image.jpg` for a different image while the WebRTC session negotiates.
+- The viewer automatically re-requests the stream after a disconnect. You can set `RN_DEBUG_DISPLAY=1` while testing to see the splash state transitions and retry logs.
+
 ##### Changing video input sources
 
 Using `gst-device-monitor-1.0` will list available devices and their 'caps', or settings.  This can help determine what GStreamer pipeline changes need to be made in the script or getting info about what video format options are available for your device.
@@ -1012,6 +1023,7 @@ curl -X POST -F "record=meeting_2024_01_22" -F "process_pid=12345" -F "language=
 ## Recent Changes
 
 ### January 2025
+- **Viewer splash pipeline & auto-reconnect**: Viewer mode now keeps the HDMI sink alive when a publisher disconnects, continuing to show the idle splash instead of a black frame. Customize the visuals with the new `--splashscreen-idle` and `--splashscreen-connecting` options; the viewer automatically re-requests the stream after graceful disconnects.
 - **NDI Direct Mode Now Default**: Changed `--room-ndi` to use direct mode by default, creating separate audio/video NDI streams to avoid combiner freezing issues. Added `--ndi-combine` flag for users who need the problematic combiner mode.
 - **Fixed NDI Freezing Issue**: Implemented workaround for ndisinkcombiner freezing after ~1500 buffers by defaulting to direct NDI mode with separate streams.
 - **HLS Recording Support**: Added HLS (HTTP Live Streaming) recording with automatic VP8 to H.264 transcoding. Creates segmented TS files and M3U8 playlists for easy HTTP streaming.