Scripts/integration test runner

[mehmetyavuzz43]

Adds a Python script to run integration tests under tests/integration, ensuring proper PYTHONPATH setup.

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[!NOTE] Introduces minimal tooling for local sanity checks and running integration tests.

• Adds scripts/bash/check_env.sh to verify .env exists and required vars (POLYGON_WALLET_PRIVATE_KEY, OPENAI_API_KEY) are set, failing fast if missing
• Adds scripts/python/run_integration_tests.py to execute pytest in tests/integration/ with PYTHONPATH set to the repo root; exits cleanly if the directory is absent

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