test: add comprehensive tests for normalize and dynamic emissions modules

[aviu16]

Summary

• Adds 37 unit tests (537 lines) covering normalize_rewards_linear() and apply_dynamic_emissions_using_network_contributions()
• Tests edge cases including empty inputs, single miners, uniform/non-uniform rewards, zero totals, and boundary conditions
• Validates emission floor/ceiling behavior, network contribution scaling, and mathematical correctness of normalization

Test plan

• Run pytest tests/validator/test_normalize_and_dynamic_emissions.py -v to verify all 37 tests pass
• Confirm no regressions in existing test suite with pytest tests/

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Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com