second maintainer, and co-equality

Abram Demski (abramdemski) joins the maintainer set, in CODEOWNERS and tests/path_gate.py, each pointing at the other with the rule that the two must agree. Maintainers are co-equal: any maintainer's review satisfies a maintainer-review requirement, including self-review, with the dated ledger entry as the review record. No two-human gates anywhere. At this scale the ledger and git history are the accountability mechanism, and a repository owner's admin rights make a self-binding two-human rule unenforceable anyway.

This partially amends the names-off posture: maintainer handles are necessarily public in a public repository. Prose-level anonymity of the program is unchanged.