Clarify cycle stepper reset inlining

PerfectNumbers.Core/RationalHelper.cs

@@ -10,17 +10,24 @@ public static class RationalHelper
         long numerator = checked((long)Math.Round(value * scale));
         long denominator = scale;
         long gcd = (long)BigInteger.GreatestCommonDivisor(numerator, denominator);
+        // TODO: Replace the BigInteger-based GCD with the UInt128-friendly binary GCD helper so this rounding path avoids
+        // allocating big integers for hot rational conversions.
         return ERational.Create(EInteger.FromInt64(numerator / gcd), EInteger.FromInt64(denominator / gcd));
     }
 
     public static EInteger ToEInteger(BigInteger value)
     {
+        // TODO: Cache a reusable byte buffer here so converting to EInteger no longer allocates per call when parsing alpha
+        // tables.
         return EInteger.FromBytes(value.ToByteArray(), true);
     }
 
     public static ulong FloorToUInt64(ERational value)
     {
         EInteger ei = value.ToEInteger();
+        // TODO: Inline this floor conversion with the span-based ladder that dominated
+        // ResidueComputationBenchmarks so the CPU path skips the expensive ERational ->
+        // EInteger materialization when reducing large 2kp+1 divisors.
         return ei.ToUInt64Checked();
     }
 
@@ -29,6 +36,9 @@ public static class RationalHelper
         EInteger ei = value.ToEInteger();
         if (value.CompareTo(ERational.Create(ei, EInteger.One)) > 0)
             ei += EInteger.One;
+        // TODO: Replace this ceiling branch with the branchless adjustment measured fastest
+        // in ResidueComputationBenchmarks so large-divisor scans avoid repeated ERational
+        // conversions on the CPU hot path.
         return ei.ToUInt64Checked();
     }
 }