gitignore: ignore Python bytecode/pytest caches (tests/mcp)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: gustavo-grieco

.gitignore

@@ -22,3 +22,9 @@ crytic-export/
 echidna.cabal
 *.swp
 profiles/
+
+# Python (MCP test suite under tests/mcp/, helper scripts)
+__pycache__/
+*.py[cod]
+.pytest_cache/
+.venv/