Fix Ln operation and add comprehensive tests

- Fixed Ln operation to handle Value conversion before math.Log using Float64() which handles boolean conversion (true → 1, false → 0)

- Added TestLnWithBoolean and TestLnEdgeCases tests for comprehensive coverage

- Refactored operations.go into separate files (arithmetic.go, boolean_ops.go, hyper.go, stack.go, variable.go)

- Removed unused toNumber function from number.go

- Added Float64() method to Value struct for boolean conversion

1 files changed, 10 insertions, 10 deletions

diff --git a/internal/rpn/boolean_test.go b/internal/rpn/boolean_test.go
index 02c5a16..f0ced89 100644
--- a/internal/rpn/boolean_test.go
+++ b/internal/rpn/boolean_test.go
@@ -239,29 +239,29 @@ func TestMixedBooleanNumericArithmetic(t *testing.T) {
 // TestBooleanShowFormat tests that Show command displays boolean values as true/false
 func TestBooleanShowFormat(t *testing.T) {
 	tests := []struct {
-		name     string
+		name       string
 		expression string
-		expected string
+		expected   string
 	}{
 		{
-			name:     "show true",
+			name:       "show true",
 			expression: "true show",
-			expected: "true",
+			expected:   "true",
 		},
 		{
-			name:     "show false",
+			name:       "show false",
 			expression: "false show",
-			expected: "false",
+			expected:   "false",
 		},
 		{
-			name:     "show mixed stack",
+			name:       "show mixed stack",
 			expression: "1 true 2 show",
-			expected: "1 true 2",
+			expected:   "1 true 2",
 		},
 		{
-			name:     "show comparison result",
+			name:       "show comparison result",
 			expression: "5 3 gt show",
-			expected: "true",
+			expected:   "true",
 		},
 	}