CW Environment alpha100 validation

- portable CAMS sibling-shard resolution: PASS
- CAMS source-unavailable fallback: PASS
- python -S (no site-packages) for both shard cases: PASS
- existing unittest suite: 28 run, 14 skipped, 0 failures
- RAW files unchanged in tests: PASS
- final PHP/Python/JSON/package validation: see build report
