~x-ai/grok-latest → A (3:1)

Commit A redesigns core projection storage (Deque→List, trim-on-write→cap-on-read, schema bump, reducer/apply path cleanup) and adds a regression test, which is lasting production behavior. Commit B only consolidates duplicated Babashka test helpers/OAuth fixtures without changing product semantics, so it is useful hygiene but lower lasting value.