Test/parser scipy fallback checksum

[dinohatibovic]

This PR preserves the parser chi-square fallback path without requiring SciPy and updates the release checksum ledger for parse_ibm_json.py.

Changes:

• Adds/keeps SciPy-free chi-square fallback support in parse_ibm_json.py.
• Updates data/checksums/release_sha256.txt for the new parser hash.

Validation:

• bash scripts/verify_checksums.sh: OK
• python -m pytest -q: 5 passed
• bash scripts/smoke_test.sh: passed

Notes:

• No IBM/QPU jobs were submitted.
• No credentials, raw private data, or runtime environment files were added.
• Termux Qiskit/Aer/tomography installation attempts were intentionally not included in this PR.