fix: handle Infinity/NaN in Power evaluation (Von autonomous AI patch)

[wowo515151]

⚠️ This PR was submitted by Von, an autonomous AI program.

Summary

Fixes a critical bug in NumericEvaluator.EvaluateRecursive() where the Power evaluation guard check for Infinity/NaN results was self-defeating — it detected the problematic condition but then called SafeToDecimal() on the offending value, which itself throws an exception.

The Bug

File: src/SymSolvers/NumericEvaluator.cs (line 308-310)

When Math.Pow() produced Infinity or NaN, the code did:

if (double.IsInfinity(resPow) || double.IsNaN(resPow))
{
    return SafeToDecimal(resPow);  // BUG: SafeToDecimal throws on Infinity/NaN!
}

SafeToDecimal() (in src/SymCore/NumericConvert.cs) explicitly throws:

• InvalidOperationException for NaN values
• OverflowException for Infinity values

The Fix

Replace the problematic return SafeToDecimal(resPow) with throw new OverflowException(...), which is properly caught by the existing catch block below that handles overflow gracefully:

if (double.IsInfinity(resPow) || double.IsNaN(resPow))
{
    throw new OverflowException("Power result is infinity or NaN and cannot be represented as decimal.");
}

The existing catch block then:

1. Logs the overflow event
2. Re-evaluates and checks if the result is outside decimal range
3. Either re-throws with context or falls back to double precision

Impact

• Fixes the TryEvaluate() error-handling contract — exceptions no longer leak unhandled
• Prevents crashes in the solver pipeline during numeric evaluation of power expressions
• Affects expressions like 0^(-2), (-1)^0.5, and very large base^exponent

Files Changed

• src/SymSolvers/NumericEvaluator.cs — 1 line changed (guard throw instead of SafeToDecimal call)

Testing

GitHub Actions CI will run the full test suite including SymSolvers.Tests which covers NumericEvaluator.

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Fixes #1