Move gotypesissue test to _demo folder

Moved test files from _cmptest/gotypesissue/ to _demo/gotypesissue/ as requested.

Generated with [codeagent](https://github.com/qbox/codeagent)
Co-authored-by: luoliwoshang <luoliwoshang@users.noreply.github.com>

_demo/gotypesissue/README.md

@@ -0,0 +1,55 @@
+# go/types Issue Test Cases
+
+This directory contains test cases for issues with the `go/types` package in llgo.
+
+## Issue #1357: Scope.Insert segmentation fault
+
+**Status**: Known issue - requires compiler fix
+
+**Description**: Calling `types.Scope.Insert()` causes a segmentation fault in llgo but works correctly with standard Go.
+
+**Root Cause**: Compiler bug in llgo's type metadata generation. When stdlib packages (like `go/types`) access their own unexported map fields with interface values, the generated `*abi.MapType` metadata is invalid/null, causing a segfault in runtime map functions.
+
+**Test Case**: `scope_insert.go`
+
+**Expected Behavior** (with standard Go):
+```bash
+$ go run scope_insert.go
+=== Scope Insert Test ===
+
+✓ Insert successful: x
+✓ Insert failed as expected: x already exists
+✓ Insert successful: y
+
+Scope contains 2 objects
+✓ Scope length check passed
+
+All objects:
+  - x: int
+  - y: string
+```
+
+**Actual Behavior** (with llgo):
+```bash
+$ llgo run scope_insert.go
+=== Scope Insert Test ===
+
+signal: segmentation fault
+```
+
+**Technical Details**:
+- The issue is in `ssa/abitype.go` (`abiMapOf` function) and `ssa/datastruct.go` (map access operations)
+- Type metadata for maps with interface values in stdlib packages is not correctly initialized
+- The `MapAccess1`/`MapAssign` runtime functions receive null/invalid type metadata
+- This is a self-referential type generation issue specific to stdlib compilation
+
+**Workaround**: 
+- Avoid using `go/types`, `go/parser`, and `go/ast` packages in llgo programs
+- Use `reflect` package for runtime type information
+- Run code analysis with standard Go compiler
+
+**Related Issues**: 
+- #642 - Tracking stdlib package implementation status
+
+**For Developers**:
+This test case should pass once the compiler bug is fixed. It serves as a regression test.

_demo/gotypesissue/scope_insert.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"fmt"
+	"go/types"
+)
+
+func main() {
+	fmt.Println("=== Scope Insert Test ===\n")
+
+	// Create a scope
+	scope := types.NewScope(nil, 0, 0, "test")
+
+	// Test 1: Successful insert
+	obj1 := types.NewVar(0, nil, "x", types.Typ[types.Int])
+	if alt := scope.Insert(obj1); alt != nil {
+		panic(fmt.Sprintf("unexpected: insert failed with conflict: %v", alt))
+	}
+	fmt.Printf("✓ Insert successful: %s\n", obj1.Name())
+
+	// Test 2: Duplicate insert (will fail)
+	obj2 := types.NewVar(0, nil, "x", types.Typ[types.String])
+	if alt := scope.Insert(obj2); alt != nil {
+		fmt.Printf("✓ Insert failed as expected: %s already exists\n", alt.Name())
+	} else {
+		panic("unexpected: duplicate insert should have failed")
+	}
+
+	// Test 3: Insert different name
+	obj3 := types.NewVar(0, nil, "y", types.Typ[types.String])
+	if alt := scope.Insert(obj3); alt != nil {
+		panic(fmt.Sprintf("unexpected: insert failed with conflict: %v", alt))
+	}
+	fmt.Printf("✓ Insert successful: %s\n", obj3.Name())
+
+	// View results
+	fmt.Printf("\nScope contains %d objects\n", scope.Len())
+
+	// Verify expected count
+	expectedCount := 2 // x and y
+	if scope.Len() != expectedCount {
+		panic(fmt.Sprintf("unexpected: scope should contain %d objects, but has %d", expectedCount, scope.Len()))
+	}
+	fmt.Printf("✓ Scope length check passed\n")
+
+	fmt.Println("\nAll objects:")
+	for _, name := range scope.Names() {
+		obj := scope.Lookup(name)
+		fmt.Printf("  - %s: %v\n", name, obj.Type())
+	}
+}