Format Python sources with Black to fix CI formatting checks

[harvatechs]

Summary

• Ran Black formatting across ariv/ and benchmarks/
• Updated 9 Python files to match the repository formatter style
• Addresses CI failures in CI / test (pull_request) and CI / test (push) caused by formatting drift

Files formatted

• ariv/cli/arivctl.py
• ariv/orchestrator/__init__.py
• ariv/orchestrator/router.py
• ariv/runner/llama_cli.py
• ariv/scripts/convert_and_quantize.py
• benchmarks/arc_benchmark.py
• benchmarks/arc_hinglish.py
• benchmarks/run_bench.py
• benchmarks/sanskriti_eval.py

Validation

• black --check ariv/ benchmarks/ passes locally

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Codex Task