ice score: per-image ice-ring indicator plumbed through all layers

A single per-image ice_ring_score - the strongest hexagonal-ice ring band/shoulder
intensity ratio from the azimuthal profile (1 = no ice) - computed in the CPU and
FPGA analysis paths and the offline azint worker, then plumbed through every layer:
DataMessage/EndMessage, CBOR (frame_serialize), HDF5 (/entry/MX/iceRingScore),
ScanResult, receiver plots (PlotType::IceRingScore), the OpenAPI spec (plot_type +
scan_result schema, with regenerated broker/gen and frontend client) and
OpenAPIConvert, the reader + Qt viewer, and the React frontend plot. Documented in
docs/CBOR.md, docs/HDF5.md and docs/CPU_DATA_ANALYSIS.md, with the general
"add a per-image quantity" recipe added to CLAUDE.md.

Verified in HDF5: lysoC (weak ice) mean 1.23, EP_cs_01-17 (heavy ice) mean 1.67 /
max 2.23. This is a monitoring quantity - it does not gate scaling (which already
excludes all ice rings) or merging (handled by the CC1/2 ring mask).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

image_analysis/MXAnalysisWithoutFPGA.cpp

@@ -113,6 +113,8 @@ void MXAnalysisWithoutFPGA::Analyze(DataMessage &output,
     output.az_int_profile_std = profile.GetStd();
 
     output.bkg_estimate = profile.GetBkgEstimate(integration.Settings());
+    output.ice_ring_score = profile.GetIceRingScore(integration.Settings(),
+                                                    spot_finding_settings.ice_ring_width_Q_recipA);
 }
 
 void MXAnalysisWithoutFPGA::RebuildROI() {