demo/defer: add FIXME for defer in loop with variable capture issue

When defer in loop captures variables, panic exit causes issues with
preceding defer normal execution. Without variable capture, it works correctly.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: luoliwoshang

_demo/embed/targetsbuild/defer/main.go

@@ -16,7 +16,11 @@ func main() {
 		defer c.Printf(c.Str("defer in else\n"))
 	}
 
+	// FIXME(zzy): When defer in loop captures variables (e.g., defer c.Printf(c.Str("%d\n"), i)),
+	// panic exit will cause issues with preceding defer normal execution.
+	// Without variable capture, it works correctly.
 	for i := 0; i < 3; i++ {
-		defer c.Printf(c.Str("defer in loop %d\n"), i)
+		defer c.Printf(c.Str("defer in loop\n"))
 	}
+	panic("panic occured")
 }