feat(hardening): add config/bisect CLI tests and fix bisect convergence bug

- Add test_cmd_config.py: 35 tests covering show/get/set subcommands, blocked namespaces (auth.*, remotes.*), HTTPS enforcement for hub.url, TOML injection safety, --format json / --json parity, and a 50-key domain stress test. - Add --format json / -f alias to `muse config show` for consistency with the rest of the porcelain JSON output convention. - Add test_cmd_bisect.py: 21 tests covering CLI subcommands (start, bad, good, skip, log, reset), session guard (double-start rejected), invalid ref rejection, ANSI-injection sanitization, and a 50-commit stress test. - Fix bisect engine infinite-loop bug: _build_remaining() previously included bad_id in the remaining list, causing the midpoint to repeatedly point at bad_id and never converge when remaining == 2. Fix: exclude bad_id from remaining (it is already the known-bad boundary). Update termination condition from <= 1 to == 0 accordingly.