Enforce FBT001/FBT002 and N802 ruff rules

[kmarchais]

Summary

Locks in ruff enforcement of the boolean-trap rules (FBT001/FBT002) and lowercase-function-name rule (N802). N802 was already satisfied by #134; this PR adds it to extend-select so future violations fail CI. FBT requires two * insertions to mark booleans as kw-only.

Changes

• pyproject.toml — extend-select = ["FBT001", "FBT002", "N802"]
• microgen/shape/strut_lattice/abstract_lattice.py — * before cell_size / strut_joints / density in AbstractLattice.__init__
• microgen/shape/strut_lattice/custom_lattice.py — * before strut-related kwargs in CustomLattice.__init__; stale # noqa: PLR0913 removed

[kmarchais]

Folding into #136 — the fluent constructors there eliminate the positional booleans by design, so the kw-only * markers in this PR become moot. #136 will pick up the FBT001/FBT002/N802 rules in its extend-select block.