v0.17.1 — eval isolation repair

Repairs the 0.17.0 isolation contract, found by the independent closeout evaluator refuting the first baseline campaign.

Fixed

• --settings '{"enabledPlugins":[]}' was schema-invalid (array vs object map) and silently inert — user-installed plugins still loaded into "baseline" runs. The runner now builds {"<plugin>": false} for every enabled plugin from the operator's real settings, failing closed on unparseable settings or missing jq.
• Tests now assert the model call's real argv via a recording stub (no --plugin-dir in baseline legs; schema-valid disable map in both arms) — replacing printed-plan string checks.

Full changelog: CHANGELOG.md