Add workbench screenshot capture smoke

docs/CODEX_EXECUTION_LOG.md

@@ -2323,3 +2323,29 @@ Limitations:
 
 Next recommended pass:
 - Add browser screenshot artifact automation for visual regression handoff.
+
+## Sprint 59 workbench screenshot artifacts (2026-06-18)
+
+Changed:
+- Added `scripts/capture_workbench_screenshots.sh` for optional visual regression handoff screenshots.
+- The script seeds the explicit offline demo workflow, opens Overview, Data, Map, QA/QC, AI Labs, Exports and System, then writes viewport screenshots plus `manifest.json`.
+- Desktop capture is always enabled; mobile capture is enabled by default and can be disabled with `CAPTURE_MOBILE=0`.
+- Added `/artifacts/` to `.gitignore` so screenshot outputs stay local.
+- Added readiness syntax coverage and regression checks for the screenshot capture contract.
+- Updated `scripts/README.md`, `docs/TODO.md` and `CHANGELOG.md`.
+
+Tested:
+- `bash -n scripts/capture_workbench_screenshots.sh`
+- `cd backend && python -m pytest tests/test_readiness_gate.py -q` (`13 passed`)
+- `bash scripts/run_readiness_check.sh` (`221 passed`)
+- Local script execution without Playwright fails cleanly with setup instructions instead of producing partial artifacts.
+- Browser-plugin visual capture against `http://192.168.10.150:1202` created viewport screenshots for all seven workspaces with no console errors or warnings.
+
+Open:
+- Commit, deploy Tower and keep the visual artifact script available for future Playwright-enabled runners.
+
+Limitations:
+- Playwright/Chromium is intentionally optional and not added to the frontend dependency set. The readiness gate checks script syntax only.
+
+Next recommended pass:
+- Run a backend error-envelope audit for expected user-error paths.