fix: delete FifoSources before RemoveSession on reconnect failure

When monitor->ShmValid() returns false and the reconnect attempt fails,
the cleanup path erased the video_source/audio_source entries from their
maps without deleting the FifoSource objects, then called RemoveSession
on the MediaSession. Two problems:

1. ZoneMinderFifoSource is only stopped/joined in its destructor. erase()
   on a raw pointer leaks the object and leaves its read_thread_ and
   write_thread_ running.

2. The xop::H264Source / H265Source / AV1Source is owned by the
   MediaSession and gets destroyed inside RemoveSession. The orphaned
   FifoSource still holds a raw m_h264Source pointer set via
   setH264Source(); the next SPS NAL parsed by the still-running
   ReadRun thread calls H264Source::SetSPS on freed memory and crashes
   in std::vector::assign.

Stack of the observed crash:
  H264Source::SetSPS                          H264Source.h:34
  H264_ZoneMinderFifoSource::splitFrames      zm_rtsp_server_fifo_h264_source.cpp:53
  ZoneMinderFifoSource::getNextFrame          zm_rtsp_server_fifo_source.cpp:265
  ZoneMinderFifoSource::ReadRun               zm_rtsp_server_fifo_source.cpp:59

Mirror the correct order already used by the "monitor went away" path
above (lines 188-197) and by the shutdown path (lines 362-375): delete
the FifoSources first so their dtors set stop_ and join the threads,
then RemoveSession can safely destroy the H264Source.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: connortechnology

src/zm_rtsp_server.cpp

@@ -207,10 +207,17 @@ int main(int argc, char *argv[]) {
         if (!monitor->connect()) {
           Warning("Couldn't connect to monitor %d", monitor->Id());
           if (sessions.find(monitor->Id()) != sessions.end()) {
+            // Delete (not just erase) the FifoSources first: their dtors stop
+            // and join the read/write threads. RemoveSession then destroys
+            // the MediaSession which owns the xop H264/H265/AV1Source; any
+            // still-running ReadRun thread holds a raw m_h264Source pointer
+            // and will crash in SetSPS on the next SPS NAL.
             if (video_sources.find(monitor->Id()) != video_sources.end()) {
+              delete video_sources[monitor->Id()];
               video_sources.erase(monitor->Id());
             }
             if (audio_sources.find(monitor->Id()) != audio_sources.end()) {
+              delete audio_sources[monitor->Id()];
               audio_sources.erase(monitor->Id());
             }
             rtspServer->RemoveSession(sessions[monitor->Id()]->GetMediaSessionId());