`CLAWMATES_VALIDATOR_MODEL` is deployment-wide, so proving Slice 2 put a second
provider on the critical path of EVERY phase verdict. `cross_provider_judge`
deliberately does not fall back when the independent judge fails — a verdict
quietly produced by a same-family model would claim a property it does not have —
so a z.ai outage makes phases unmeetable rather than merely unverified. That is a
per-mission trade, not a per-deployment one.
`missions.validator_model` (0068), settable at create, with three distinct states
because an empty string and NULL mean opposite things in a nullable text column:
NULL use the deployment default
'' explicitly NO independent validator — judge with the house model.
The default must not quietly reinstate independence a mission was
told to skip.
'glm:glm-4.7' this spec, subject to the same three refusals as before:
same-family rejected, unregistered provider rejected, and a failed
independent judge does not fall back.
Whitespace counts as empty: a column hand-set to " " meant to say nothing.
478 tests pass, clippy clean. Behaviour is unchanged for existing missions — they
have NULL and so keep following the deployment default.
