Polish export and system mobile layout

docs/CODEX_EXECUTION_LOG.md

@@ -2824,3 +2824,27 @@ Limitations:
 
 Next recommended pass:
 - Continue with Export/System mobile-density polish, especially export action cards and provider capability lists.
+
+## Sprint 76 Export/System mobile visual polish (2026-06-20)
+
+Changed:
+- Added scan-friendly Provider Capabilities cards with structured provider header, status badge, authority/configuration/geometry/query mode fields and layer chips.
+- Added mobile-density CSS for provider cards, export action cards, export history controls and export card headers.
+- Added overflow wrapping for long provider limitations, attribution/license notes, export ids and artifact paths.
+- Added `backend/tests/test_sprint76_export_system_mobile_polish.py`.
+- Updated `frontend/README.md`, `docs/TODO.md` and `CHANGELOG.md`.
+
+Tested:
+- Red step: `python -m pytest backend/tests/test_sprint76_export_system_mobile_polish.py -q` failed on missing Export/System mobile CSS and provider markup contracts.
+- `python -m pytest backend/tests/test_sprint76_export_system_mobile_polish.py backend/tests/test_sprint75_ai_labs_mobile_polish.py backend/tests/test_sprint74_data_map_mobile_polish.py backend/tests/test_sprint31_unraid_template.py backend/tests/test_sprint64_export_handoff_polish.py backend/tests/test_sprint7b_provider_registry.py backend/tests/test_sprint30_workbench_components.py -q` (`27 passed`)
+- `cd frontend && npm run typecheck`
+- `cd frontend && npm run build`
+
+Open:
+- Run full readiness, redeploy Tower and verify live Export/System mobile polish after deployment.
+
+Limitations:
+- Frontend presentation polish only; no export workflow, provider API, persistence, migration, provider fetching or AI/model changes.
+
+Next recommended pass:
+- Continue with right-side inspector mobile polish, especially long dataset/vector/raster metadata and action groups.