Address review on #123378:
- Add enumOptionsFor('display.personality', …) tests with a root-level
`personalities` block, deriving expected built-ins from
BUILTIN_PERSONALITIES (change-detector rule). Reverting the new root
read now fails these, closing the coverage gap the reviewer flagged.
- Replace the Set-based clash assertion in personalityNamesFromConfig
with direct array equality so it pins membership, dedupe, and the
root-before-agent ordering the CLI listing uses.
afb924d841