build(make): decouple install-service from test suite, raise pytest timeout
Split `make ci` into `make install-checks` (fast deterministic gates —
format, ruff, rename gate, layer-hygiene, mypy) and `make verify`
(install-checks + tests). `make ci` still exists and runs the full
sequence; `install-service` upgrade now gates on `install-checks`
instead of the full `ci` suite, so tests can't flake under real
service load and abort the upgrade.
Raise global pytest timeout from 5s to 15s and add
@pytest.mark.timeout(30) to test_make_skills_idempotent, which is
subprocess-heavy and occasionally slow on a quiet box.
Co-authored-by: Codex <codex@openai.com>