test(dtypes): Remove 11 stale [OpenBugs] tags for Half/Complex tests

All 11 tests pass on both frameworks (net8.0 + net10.0) after Rounds 6-15
fixes. Their [OpenBugs] attribute was filtering them out of the CI
default run, hiding passing coverage. Stale tag removed along with the
inaccurate "not supported yet" comments.

Tests re-enabled in CI:
  NewDtypesArithmeticTests.cs
    Complex_Multiply                    (closed by R6)
    Complex_Multiply_Scalar             (closed by R6)
  NewDtypesComparisonTests.cs
    Half_AsType_ToComplex               (closed pre-R11)
  NewDtypesCumulativeTests.cs
    Complex_CumProd                     (closed by R7 / B18)
  NewDtypesEdgeCaseTests.cs
    Complex_Dot                         (closed by R6)
  NewDtypesReductionTests.cs
    Half_Mean                           (closed by R14 / B2+B16)
    Half_Std                            (closed by R14 / B16)
    Complex_Mean                        (closed by R14 / B2)
    Complex_Std                         (closed by R7  / B20)
    Complex_Sum_Axis                    (closed by R7  / B19)
  NewDtypesTypePromotionTests.cs
    Half_Plus_Complex_PromotesToComplex (closed pre-R11)

Full suite: 6929 -> 6940 / 0 / 11 per framework (default CI filter).

Author: Nucs

test/NumSharp.UnitTest/NewDtypes/NewDtypesArithmeticTests.cs

@@ -132,7 +132,6 @@ public void Complex_Add()
         }
 
         [TestMethod]
-        [OpenBugs] // Complex multiply not supported in IL kernel yet
         public void Complex_Multiply()
         {
             // NumPy: z * z2 where z=[1+2j, 3+4j, 0+0j, -1-1j], z2=[1+0j, 0+1j, 1+1j, 2+2j]
@@ -149,7 +148,6 @@ public void Complex_Multiply()
         }
 
         [TestMethod]
-        [OpenBugs] // Complex multiply not supported in IL kernel yet
         public void Complex_Multiply_Scalar()
         {
             // NumPy: np.array([1+2j, 3+4j, 0+0j, -1-1j]) * 2

test/NumSharp.UnitTest/NewDtypes/NewDtypesComparisonTests.cs

@@ -254,7 +254,6 @@ public void Half_AsType_ToDouble()
         }
 
         [TestMethod]
-        [OpenBugs] // Half to Complex conversion not supported yet
         public void Half_AsType_ToComplex()
         {
             // NumPy: np.array([1.5, 2.5, 3.5], dtype=np.float16).astype(np.complex128)

test/NumSharp.UnitTest/NewDtypes/NewDtypesCumulativeTests.cs

@@ -102,7 +102,6 @@ public void Complex_CumSum()
         }
 
         [TestMethod]
-        [OpenBugs] // CumProd not supported for Complex yet
         public void Complex_CumProd()
         {
             // NumPy: np.cumprod(np.array([1+1j, 2+2j, 3+3j]))

test/NumSharp.UnitTest/NewDtypes/NewDtypesEdgeCaseTests.cs

@@ -282,7 +282,6 @@ public void Half_Dot()
         }
 
         [TestMethod]
-        [OpenBugs] // Dot not supported for Complex (multiply not working)
         public void Complex_Dot()
         {
             // NumPy: np.dot([1+1j, 2+2j], [1-1j, 2-2j]) = (10+0j)

test/NumSharp.UnitTest/NewDtypes/NewDtypesReductionTests.cs

@@ -166,7 +166,6 @@ public void Half_NanSum()
         }
 
         [TestMethod]
-        [OpenBugs] // Mean division not supported for Half yet
         public void Half_Mean()
         {
             // NumPy: np.mean(np.array([1.0, 2.0, 3.0, 4.0, 5.0], dtype=np.float16)) = 3.0 (dtype: float16)
@@ -189,7 +188,6 @@ public void Half_NanMin()
         }
 
         [TestMethod]
-        [OpenBugs] // Std not supported for Half yet
         public void Half_Std()
         {
             // NumPy: np.std(np.array([1.0, 2.0, 3.0, 4.0, 5.0], dtype=np.float16)) = 1.4140625 (dtype: float16)
@@ -235,7 +233,6 @@ public void Complex_Sum()
         }
 
         [TestMethod]
-        [OpenBugs] // Mean division not supported for Complex yet
         public void Complex_Mean()
         {
             // NumPy: np.mean(np.array([1+2j, 3+4j, 0+0j, -1-1j])) = (0.75+1.25j) (dtype: complex128)
@@ -247,7 +244,6 @@ public void Complex_Mean()
         }
 
         [TestMethod]
-        [OpenBugs] // Std not supported for Complex yet
         public void Complex_Std()
         {
             // NumPy: np.std(np.array([1+0j, 2+0j, 3+0j, 4+0j, 5+0j])) = 1.4142135623730951 (dtype: float64)
@@ -259,7 +255,6 @@ public void Complex_Std()
         }
 
         [TestMethod]
-        [OpenBugs] // Axis reductions not supported for Complex yet
         public void Complex_Sum_Axis()
         {
             // NumPy: np.sum(np.array([[1+2j, 3+4j], [5+6j, 7+8j]]), axis=0) = [6+8j, 10+12j]

test/NumSharp.UnitTest/NewDtypes/NewDtypesTypePromotionTests.cs

@@ -74,7 +74,6 @@ public void SByte_Plus_FloatScalar_PromotesToFloat64()
         #region Half + Other Types
 
         [TestMethod]
-        [OpenBugs] // Half + Complex type promotion not fully supported yet
         public void Half_Plus_Complex_PromotesToComplex()
         {
             // NumPy: float16 + complex128 = complex128