Scaffold freeroute: Python port of the FreeRouting engine

Pure-Python PCB autorouter replacing the freerouting.jar step in kicad-mcp.
Contract is Specctra DSN in, SES out — a drop-in for the JAR so the toolchain
needs no JVM. Includes pyproject (uv/ruff/pytest, src-layout) and a porting
plan seeded for study of the upstream FreeRouting Java source.

.gitignore

@@ -0,0 +1,22 @@
+# Python
+__pycache__/
+*.py[cod]
+.venv/
+venv/
+dist/
+build/
+*.egg-info/
+
+# Test / coverage
+.pytest_cache/
+.ruff_cache/
+.coverage
+coverage.xml
+htmlcov/
+
+# Reference source (cloned, not vendored — see docs/PORTING_PLAN.md)
+/reference/
+
+# Editor / OS
+.DS_Store
+*.swp