v0.1.0 — compatibility contract

First release — changelog is the contract.

Stable from this tag: intent.csv / rules.csv, CLI 17 commands (fiducial.py:1252), exit 0/1/2 (fiducial.py:15), JSON shapes, SchematicBuilder API (schematic_builder.py:144).

• Tests: 117 OK (10 skipped) — PCB drc/render now regression-covered (08bc7b6 tests/fixtures/healthy.kicad_pcb:1)
• Corpus: 153 schematics (kicad-demos 116 + ZSWatch 9 + cynthion 17 + launch 11), nightly green
• Docs: CHANGELOG.md:1 + docs/explanation/compatibility.md:1 + docs_check.py clean

See CHANGELOG.md for the full table. From here, any breaking CLI/CSV/JSON change requires a minor bump.