receiver: stills live counts a frame as received before it takes a slot

The live status's images_received, the frame rate and the end latency of a
stills collection ran from StillsGPUAnalysis::Hold, which only sees the frames
that got a slot of the image buffer: a frame dropped at a full buffer was not
counted, so after a loss the "N / M · Hz" header and the latency figure ran
from the last frame rugnux kept, not the last frame the detector sent. The
receiver now reports the frame to the live status in OnImage, before the slot
is taken, as the rotation receiver does; the drop itself is unchanged.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HVeDQsU5a8AJUdJPgWevAK

receiver/JFJochReceiverRugnuxStills.cpp

@@ -66,6 +66,7 @@ void JFJochReceiverRugnuxStills::OnImage(uint32_t id, DataMessage &message, std:
         logger.Error("Dropping image {} - the collection has {} images", message.number, experiment.GetImageNum());
         return;
     }
+    live_status.ImageReceived(received);
     CountImage(message);
     const size_t size = message.image.GetCompressedSize();
 

receiver/StillsGPUAnalysis.cpp

@@ -67,7 +67,6 @@ void StillsGPUAnalysis::Publish() {
 }
 
 void StillsGPUAnalysis::Hold(const std::shared_ptr<HeldImage> &image) {
-    status.ImageReceived(std::chrono::steady_clock::now());
     queue.PutBlocking(image);
     {
         std::unique_lock ul(prepass_mutex);

tests/StillsGPUAnalysisTest.cpp

@@ -114,8 +114,10 @@ TEST_CASE("StillsGPUAnalysis_FailingFrameDoesNotStopAnalysis", "[StillsGPUAnalys
     };
     StillsGPUAnalysis gpu(x, mask, Start(x), nullptr, 1, 100, logger, sink, status);
     // The frames carry no image, so their analysis fails too - they are passed on all the same.
-    for (int i = 0; i < 3; i++)
+    for (int i = 0; i < 3; i++) {
+        status.ImageReceived(std::chrono::steady_clock::now());   // as the receiver does before it holds a frame
         gpu.Hold(Frame(buffer, i));
+    }
     REQUIRE_NOTHROW(gpu.Finish());
     CHECK(sunk == 3);
     // The outcome waits for everything to be written, and comes after the latency.