Scaffold gausse coilgun simulator project

src-layout Python package with CLI stub (sweep/evolve/simulate/report
subcommands), pyproject.toml pinned to numpy/scipy/matplotlib, and PLAN.md
tracking the implementation roadmap.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,13 @@
+__pycache__/
+*.py[cod]
+*.egg-info/
+.pytest_cache/
+.venv/
+venv/
+build/
+dist/
+*.sqlite3
+*.sqlite3-wal
+*.sqlite3-shm
+out/
+.DS_Store