Polish project report artifact

backend/README.md

@@ -563,6 +563,17 @@ If `rasterio` is unavailable:
 - raster metadata responses return `503` with `RASTER_PROCESSING_UNAVAILABLE`
 - raster clip/tile endpoints return explicit unavailable responses
 
+## Export report artifact
+
+`POST /api/v1/exports/report` creates the existing lightweight
+`project_report_html` artifact. The report is a self-contained HTML handoff
+view rendered from persisted project, dataset, QA/QC and export-history state.
+It includes readiness scorecards, dataset inventory, QA/QC evidence, artifact
+history, known limitations and print-friendly CSS.
+
+This remains a simple HTML export. It does not add a PDF designer, report
+builder, live provider fetching or new analysis behavior.
+
 ## Helpful repository scripts
 
 - `bash scripts/backend_install.sh`