chore: scaffold payroll extension

Repo tooling and LNbits extension metadata only — no runtime code yet, so
this lands separately from the feature work per the workspace commit rules
(cross-cutting concerns commit first).

- MIT licence, .gitignore, README
- Makefile + pyproject wired for the standard aio fork lint pipeline
  (black + ruff + mypy) and pytest
- config.json declaring id/version/tile so the extension is installable
  from the aiolabs catalog once there is something to install

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018jy52j9GRZ6XKa1Zt21LLj

Makefile

@@ -0,0 +1,32 @@
+all: format check
+
+format: black ruff
+
+check: mypy checkblack checkruff
+
+mypy:
+	uv run mypy .
+
+black:
+	uv run black .
+
+ruff:
+	uv run ruff check . --fix
+
+checkruff:
+	uv run ruff check .
+
+checkblack:
+	uv run black --check .
+
+test:
+	PYTHONUNBUFFERED=1 \
+	DEBUG=true \
+	uv run pytest
+
+install-pre-commit-hook:
+	@echo "Installing pre-commit hook to git"
+	uv run pre-commit install
+
+pre-commit:
+	uv run pre-commit run --all-files