add .gitignore

Covers the usual Python noise (__pycache__, .venv, tooling caches),
common secrets paths (.env, config/settings.local.toml), editor/OS
junk, and stray SQLite files in case anyone points db_path at a
repo-local path. Nothing to scrub from history — none of these were
ever tracked.

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,45 @@
+# Python bytecode + caches
+__pycache__/
+*.py[cod]
+*$py.class
+*.so
+
+# Build / packaging
+build/
+dist/
+*.egg
+*.egg-info/
+.eggs/
+
+# Virtual environments
+.venv/
+venv/
+env/
+ENV/
+
+# Tooling caches
+.pytest_cache/
+.mypy_cache/
+.ruff_cache/
+.tox/
+.coverage
+.coverage.*
+htmlcov/
+
+# Secrets / local config
+.env
+.env.local
+config/settings.local.toml
+
+# Editor / OS noise
+.idea/
+.vscode/
+*.swp
+*.swo
+.DS_Store
+Thumbs.db
+
+# Runtime artifacts (only if someone points settings.toml at a repo-local path)
+*.db
+*.sqlite
+*.sqlite3