chore: add contribution workflow and experiment templates

.gitignore

@@ -0,0 +1,28 @@
+# Local configuration and credentials: review content before every commit.
+.env
+.env.*
+!.env.example
+!.env.sample
+*.pem
+*.key
+
+# OS and editor noise
+.DS_Store
+Thumbs.db
+*.swp
+*.swo
+*~
+
+# Common local dependencies and caches
+node_modules/
+.venv/
+venv/
+__pycache__/
+*.py[cod]
+.pytest_cache/
+.mypy_cache/
+.ruff_cache/
+coverage/
+.cache/
+
+# Add experiment-specific generated files in that experiment's .gitignore.