Add runtime limit and summary output to performance mode

[3rdIteration]

Summary

• add a --performance-runtime option that validates input and stops performance runs automatically
• track performance test timing and print a final average kP/s summary when exiting
• treat completed performance runs as successful in the btcrecover entry point

Testing

• python run-all-tests.py

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https://chatgpt.com/codex/tasks/task_e_68e2caa5897c83229db1f9e3b9c5dd16