fix(dpp)!: version-gate distribution function floating-point evaluation

[PastaPastaPasta]

Issue being fixed or feature implemented

DistributionFunction::evaluate() uses f64 transcendental functions (powf/exp/ln) to compute consensus-critical token rewards. The std implementations are platform-dependent (varying across CPU architectures and libm versions), risking consensus divergence between nodes computing different integer rewards for the same claim.

Concrete proof: 125^(1/3) yields 4 on some platforms (std powf) vs 5 on others. The deterministic libm path always returns 5.

What was done?

Gate transcendental float operations behind distribution_function_evaluate_version in DPPTokenVersions:

• Version 0 (all current protocol versions through v12): preserves original std behavior (.powf(), .exp(), .ln())
• Version 1+: uses deterministic libm functions (pow, exp, log)

Changes:

• Add distribution_function_evaluate_version field to DPPTokenVersions
• Create TOKEN_VERSIONS_V3 with deterministic evaluation enabled (for use in a future protocol version)
• Add libm = "0.2" dependency to rs-dpp
• Thread platform_version through evaluate() → evaluate_interval() → rewards_in_interval() call chain
• Version-gate 4 transcendental call sites: Polynomial (pow), Exponential (exp), Logarithmic (log), InvertedLogarithmic (log)
• 5 unaffected variants use only integer math: FixedAmount, Random, StepDecreasingAmount, Stepwise, Linear

Note: TOKEN_VERSIONS_V3 is created but not yet assigned to a platform version. A future PR creating PLATFORM_V13 should reference it to activate deterministic evaluation on the network.

How Has This Been Tested?

• All 50 evaluate() unit tests pass (47 existing + 3 new determinism tests)
• All 82 validation.rs tests pass
• All 72 evaluate_interval tests pass (with token-reward-explanations feature)
• Determinism regression tests for all 4 affected variants using distribution_function_evaluate_version = 1
• cargo check -p dpp -p drive compiles clean

Breaking Changes

Function signature changes (compile-time only, no behavioral change for existing protocol versions):

• DistributionFunction::evaluate() now requires platform_version: &PlatformVersion
• DistributionFunction::evaluate_interval() now requires platform_version: &PlatformVersion
• RewardDistributionType::rewards_in_interval() now requires platform_version: &PlatformVersion

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

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