~x-ai/grok-latest → A (2:1)

A removes dual-path legacy projection helpers (_legacy_commit_row, _legacy_observation) and all GitDiscovery/Emission fallbacks from epoch/commit pages and downloads, forcing Evidence envelopes only (with required Emission fields and updated tests), a lasting schema/design cleanup; B is a correct but narrower XSS fix that adds ammonia sanitization of body_html at two PreEscaped sites plus unit tests.