v0.1.0b2

add a pre-push mypy hook (only mypy; lint/tests stay where they belong)

Type-check at pre-push via make typecheck — the one check that is expensive
and venv-dependent enough to skip per-commit but worth catching before a push.
default_install_hook_types makes make hooks wire both stages in one
pre-commit install. Pin trailing-whitespace and end-of-file-fixer to
pre-commit (they ship stages including pre-push upstream) so pre-push is mypy
only: fixers mutate files, which is fine at commit-time but awkward after a
commit exists. Tests are not a hook at any stage — they need a live Postgres.