session-close: write the handoff, fail if the card is empty

A coding session ends. The next one starts from zero.

session-close is a local Python CLI. You fill a close card. It checks the fields, then writes SESSION_LOG.md (prepend one entry) and NEXT.md (open items + exactly three opening lines). Empty skeleton fails: doctor exit 2, no files written. status is read-only git. It does not commit.

It is not a model. It is not Superpowers or GSD. It is not on PyPI. Clone, then:

python3 -m venv .venv
.venv/bin/pip install -e .
./session-close doctor --in examples/ok.json
./session-close emit --in examples/ok.json --root .

Skill install is instructions only. It does not install the Python package:

npx -y skills add jennifferweslowski-design/session-close

Repo: https://github.com/jennifferweslowski-design/session-close