refactor: rename reflect-indirect to reflectindirect

Follow naming convention of other demo folders (reflectfunc, gotime, etc.)

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Co-authored-by: luoliwoshang <luoliwoshang@users.noreply.github.com>

_demo/go/reflectindirect/reflect-indirect.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"reflect"
+)
+
+func main() {
+	x := 42
+	p := &x
+
+	// Test 1: Non-pointer value - should return same value
+	v1 := reflect.Indirect(reflect.ValueOf(x))
+	if !v1.IsValid() || v1.Interface() != 42 {
+		panic("Non-pointer test failed: expected 42")
+	}
+
+	// Test 2: Pointer - should dereference
+	v2 := reflect.Indirect(reflect.ValueOf(p))
+	if !v2.IsValid() || v2.Interface() != 42 {
+		panic("Pointer dereference test failed: expected 42")
+	}
+
+	// Test 3: Nil pointer - should return invalid Value
+	var nilPtr *int
+	v3 := reflect.Indirect(reflect.ValueOf(nilPtr))
+	if v3.IsValid() {
+		panic("Nil pointer test failed: expected invalid Value")
+	}
+
+	println("PASS")
+}